there were a bunch of h60 parts on e-bay recently. You probably will need to find an h60 crank. I forgot exactly how it goes but I think that the h50 and h60 have the same bore size but the crank stroke is different. The h60 and h70 have the same crank stroke but the bore is larger on the 70. I don't know if the h70 crank will work because I think the rod journal is larger on the h70. But if you use the h70 rod with the crank in the h60 block it might not matter except if the h70 is a 1" shaft. I don't know if the crank from a ball bearing engine is different.