I have to ask a question first, is the flywheel not have the dowel pin hole in it or is that the problem? If it is but there is 4 holes that treaded there, you can get drive adapter at
www.midwestsupercub.net something pull you so there no limited on flywheels. I hope this helps but if it don't please if it don't give me more info and I will see what else i can come with. If it has a flat oil pan it may cause a driveshaft issues due to different height from base to center of flywheel but most blocks you can put cub style oil pan.
Jeremy