Hi Farmer, I think the crankshaft should be OK, unless you are going to be relying on this engine as your primary mover. The crank could easily be reground, bearing shells come in under sizes of 10, 20, 30 & 40 thousandths of an inch. What condition is the little end bush in? Not a difficult/expensive replacement, some need reaming to size after fitting.
Diesel engines are a little different to petrol engines, when running them in it is essential to have a sizeable load on the engine or the bores will become glazed and you will not get good compression.
The plunger mechanism is exactly what it looks like: a syringe. You fill the reservoir with engine oil and push the plunger down, this oil then sits on top of the piston increasing the compression ratio for easier cold starting.
Starting these is relatively simple, especially with an electric start. Check the injector pump rack is fully open, bleed the fuel system at each point, there are little bleed screws on the fuel filter and etc. Work your way from the fuel tank to the injector pump, once you have fuel flowing from the top of the injector pump fit the high pressure pipe, do not do up the nut at the top where it fits onto the fuel injector, leave it slightly loose. Crank the engine over until you get fuel squirting out around the loose nut, now do it up. Crank the engine over a few times and it should start.
Good luck.
Bob