The best way to set the RPM on a AC generator is to measure the frequency of the AC power.  There are several power monitors on teh market, probably one of the most common is a device called the kill-o-watt.  You sound like you are not in the USA?  I am sure there is probably something similar available where you are at.  These devices are used to measure power consumption on appliances(plugs into wall and appliance plugs into it), but also typically displays voltage and frequency

As for the capicator , upping the value may get the output to where you need to be, just be carefull you don't overdo it...

If you use the smaller radiator, you may need to raise it a little higher than the top of the cylinere head to assist thermosiphon. 

The issue I have with a large radiator if you don't employ some fan/air control is the same issue I have with drum cooling.  The large radiator is capable of providing too much cooling.  this will cause the thermostat to cycle and the engine to continously gulp cold coolant instead of stabelizing at a steady flow and temperature.  This happens on semi's in the winter.  they have a monster radiator to allow them to cross the desert in summer, but in winter it provides waaay too much cooling.  That is why you see the covers with zippers over the grills of big rigs in the winter.  The zipper allows the driver to adjust the airflow thru the radiator to match the heat output and maintain steady coolant flow thru the system without removing too much heat from the coolant.

It could be that teh original heatex was way overspecced for the ammount of heat it must transfer, so the smaller heatex may be OK.  you would have to run some numbers to confirm this of course...

Be carefull with the copper, if you have any movement, it will eventually work harden and crack.  I use steel brake lines for these type things.  They are a little tougher to bend, but they are pretty bullet resistant. The flare fittings also seal well and th assembly once bent and fitted disassembles easilly.  That is the beauty of the CS design, the oil slung by the dipper mostly runs back into the upper sump so the engine isn't going to self destruct immediately if the pump quits..

+1, pull that sucker apart!  I got nearly a half cup of sand and casting flash out of the inside of my cylinder after I pressed the cylinder liner out.  Once apart take a scribe and scrape/punch/push around all over the inside of the case.  What you are looking for are pockets of casting sand that were painted over. The sharp point of a scribe will push thru the paint into these pockets.  A pressure washer may dislodge them also but the inside surface is difficult to cover completely...  As mentioned disassemble the piston completely.  Any sand up inside the dome WILL trickle down and wipe your main rod bearings and perhaps kill your crank.  This alone is enougn reason to pull and check it so you don't kick yourself later... 

What type sump do you have.  Mine had the traditional tip out section where the filler plate used to be located on the original listers except mine was cast shut.  This section had no paint down inside the tipout on the upper side.  It also was not cleaned of sand.  If your block is like this reach down thru the main access door and put your fingers up against the roof of this section and you will probably feel what I am talking about.   This will also give you an opportunity to paint the inside properly(cuts way down on oil weeping thru the porus cast iron).

If the piston top is parallel to the crank(along the same axis as the wrist pin and crankshaft) a mis-alignment of the cylinder bore for which a half gasket would compensate will show itself as differential squish.  The holes in the side of my block where the crankshaft roller bearing carriers set, were not bored parallel to the deck.  But my piston top was parallel to the crankshaft(machinists level can help you check this also).  So when I installed the cylinder without a half gasket, this angular difference showed up in the differential squish.  The difference in squish across the 4" piston equaled the angular offset between my crank and deck. That told me the cylinder top and bottom were at least parallel, but not if the installed cylinder formed a parallellogram or a rectangle.   It also created a wicked offset of the piston on the wrist pin from crank up to crank down:  As 38ac mentioned, that is the important part to align the cylinder to, either by using a half gasket to align the cylinder bore or by relocating the crank bearings to align the piston axis to the deck and cylinder.  The point I am getting at is that if the piston to rod offset is small from full up to full down, you are probably going to have a pretty small differential squish across he piston top over the wristpin ends.

The cylinder/liner true can be checked fairly easilly on a large drill press.  I put two bolts into the drill press table slots that would fit inside the cylinder when it is placed onto the table over the bolts.  I would have them touch the inside of the cylinder around the 3 and 6 Oclock positions.  I clamp a rod with a dial indicator into the chuck and position it down inside the top of the cylinder with it's measurement rod touching the cylinder top between but directly above the two bolts.  You rotate the cylinder slowly keeping the bottom inside edge of the cylinder against the two bolts.  As you rotate the cylinder watch the dial indicator.  If the cylinder bore is perpendicular with the lower surface, the dial indicator measurement should stay constant thru 360 degrees of rotation.  If it varies thru 360 degrees, something is out of true.  I have a pic somewhere of this setup, I will see if I can locate it and post it...     

What Mike said.  Te split collar like he pictured is what you want.  I ordered mine thru fastenall.

That key pic initially posted almost looks like it would if the wheel was on the shaft backwards... 

The key holds the wheel on the shaft mainly thru friction between the inside of the hub and the shaft opposite the keyway.  Jacks article is great particularly in the area of metal prep to help reduce corrosion once the assembly is put together. 

One hint I will add is that it is way easier to seat the key initially if you rotate the shaft so the keyway is on the bottom.  That way the contact area in the hub is already fully in contact with the shaft and you are not having to lift it with the key taper like you would be if the keyway is pointing up.

Indian machine work being what it is. I would definitely check that the key taper matches the flywheel taper.  Keyway down helps with the test fitting process as well.  I used candle soot on the key and looked for witness marks on the key after lightly tapping the key into the keyway and filing where the contact marks are untill the contact area covers as much of the key surface as possible.  The keys that came with mine were off by a considerable ammount... The flywheel keyway taper was also not constant(easilly seen with a straightedge) on one of my wheels and required a little filing to fix.  The important thing to consider with a listeroid is to take nothing for granted:) 
Good Luck.       

The air pipe opening is only placed just below the surface level of the lower sump.  Any crud should have settled down near the bottom, you know where the oil pump pickup is:).  This should really be the case if the engine has set a while.  It might also be an indication of lower sump oil level.  It will sound different when it isn't shooting any oil, or dosn't shoot oil for as long.  If you have an air gun, attach a long pipe to it and put a cup or two of oil in a clear gallon jug.  Stick the airpipe down into the oil and give it a shot.  A rag loosely over the opening is advisable:)  Bending the airpipe end or drilling a hole in the side of the pipe so you can direct the airstream up thru the oil really enhances the effect.  Basically it will look like a bomb went off inside the jug, hence the name...