You have done well not to have to re ring or re bore it after all this time. I certainly agree, good racing grade oil is essential rather than that Lawnmower quality crap. Make a huge difference to longevity.

I remember mowing the lawn in my early '20s at my Aunts place. Head gasket on the mower blew. was sunday afternoon so no places to get a spare so I got some single ply cardboard from a shirt box I think it was, Got a punch from my uncles  shed and cut a rough gasket shape.
Didn't pay much attention to the inside, figured it would burn away as needed.  Put it on and the thing fired right up.
Thing kept going longer than my aunt and uncle eventually did.

I dumped about a dozen Milk crates of Victa parts when I moved about 3 years ago. Wasn't an easy thing to do actually. Just didn't have any use for them and I'd sold all the complete engines. I do miss the sound and smell of and working on those little engines.
 Still have one mower, must get it out and give it a fire up.  Used to wake up to the sound of those things in the neighbourhood every weekend as a kid.  Now all I hear is large 4 stroke singles on ride ons hammering away. 
Nothing like the sound of the 3 Cyl Diesels in both my Kubotas.

Maybe you could put this engine on an Old slasher and tow that round to make a franken mower?  :0)

Have you anything you intend to couple it up to?
I always prefer to see these engines at Rallies doing SOMETHING rather than just Idling doing nothing. Pumping water round or driving some sort of genny to light a build I think is always  better than just ticking over on their own.
Always figure that can't be great for them.

A rebuilt old engine should have a much longer  life before another rebuild considering the quality of the oils we have now that probably couldn't even been Imagined  50-80 years ago.

When I used to build a lot of 2 Stroke engines, I used to pack the Roller bearings with a good amount of grease.
Also used to put a good smear in behind the rings and wipe Grease around the bore.
For 2 strokes I used to run a rich oil mix for an hour so so break in., People used to tell me that wouldn't let the rings seat properly but I never had a problem with that.  I also put a bit of oil in the fuel of 4 strokes when I rebuild them. Not much, only about 100:1 but I think it helps.
I also pack seals with grease and smear shafts with it before putting them through the seals.

One trick I rad of with 2 strokes was to put a chamfer of about 2-3mm around the edge of the piston skirt. This was said to let the oil film get between the piston and the skirt rather than the sharp edge take it off.  I thought that made a lot of sense and have done it on all engines.
My 2 strokes used to get thrashed but I always got fantastic life out of them.I think that trick was a big reason why.

The other thing was always run plenty of oil. Never gave a damn what the manufacturer said, I ran the oil according to what the thing was doing at the time and always more than suggested. A lot of people seem to have a phobia about 2 strokes blowing smoke. I got worried it they weren't!  If the recommendation was 50:1, I'd run 32. If I was thrashing on the things real hard, I'd run 25.

As long as there was very little or no oil coming out the exhaust pipe, I was happy. harder a 2 stroke works, the more oil you can throw at it.
I like to put grease everywhere in rebuilt engines, even on the rockers and vale stems. It will either burn off or dissolve into the oil depending where you put it and all works well.

Other thing I have always done on a pressurised engine is crank it till the oil pressure comes up.  Astounds me when people fire new engines without doing that. seen plenty of vids where people fire engines and then the oil pump takes a minute or something to prime.  That engine has a short life before the thing has begun.

I'm sure John what you have done may not be to spec but it will work well. You can get away with a lot with old engines but I think people also have a good understanding of things that may not have been thought of back then and changes you have made will probably be for the better.

Thanks Glort, I too am anxious to hear the mongrel run again. Not sure at what level it will run at but the aim is for it to be loud and dribbling oil somewhere and blowing smoke.
I have a list of things that might be wrong in what I have done and the cam gear rebuild done to a guess shape is high on the list of things. The spring tension for the needle in the injector is another. Tomorrow I want to make some caps for the valves and with a special design to do the job so will take some pics of the design. It is a combination of the originals and something new.

Got the rings onto the piston and gapped them using the cut off wheel of my grinder. (that will be a talking point).
Fitted the piston then the crank into place and connected the big end to the conrod and then to the crank. Made a new gasket out of 1.5mm paper for the side cover that houses the other crank main, fitted a new oil seal and then put the cover on and tightened it. The rings a have a good hold of the bore but once I have it moving I can move it with a struggle by turning the crank by hand. Once the flywheels are on it will be a lot easier.

Spotless !
I bet the inside of your engine cooling passages are just as clean.
Nice work.