I have a 72 ds7 and was wondering if anyone knows what other top ends will fit. i have lots of engines but the ds7 is my only complete bike. i have a 74 rd250 (reed valve), a 72 r5 350 (piston port, a 74 rd 350, and a77 rd 400. I think they all had the same stroke, but not sure if cylinders will fit.also will the six speed trans fit into the ds7 cases? Thanks Justin