Had a rough go at it. The engine is a little tight from the fresh rings, honed cylinder, seals and bearings. I can get it spinning but once I flip the compression release it will not go over compression. Two of us gave it our best but it wore us out. Also the engine is close to the floor on a couple of 6X6's Crank center is low so you really have to bend over. Lastly, I fitted a Lister crank since this engine was missing the original one. The compression stroke is on the upswing of the crank. You cannot throw your weight into rolling it over at the toughest part.
So I have rigged a coupling to spin it with a tractor PTO. Not done yet but all I need to do is finish up the "dog" that engages the keyway.
Bob