I have 2 engines for my kr-1. engine A has blown crank seals (I am told) and a good top end, Engine B has a broken top end.
I have tried to simply bolt on the top end of engine A onto engine B, but when looking at the crank case it seems we have a stripped thread on the lower crank case near the crank bearing. (bolt

So the plan is now to use the crank case from engine A and just pop the crank from engine B in and re-assemble.
Looking at the crank from engine A however, I can see no discernible difference between the two.
Do I just bite the bullet and send the crank off to stan stephens and that way I know the crank has been properly seen to, or do I risk it and bung in the crank from engine B?
Anything I can do to test these cranks and see if they work properly?
Thanks
Rick