I'll admit ramman that i don't have a lot of knowledge swapping early and late covers and balancers. I'm assuming that since the cranks are interchangable, the crank keys are in the same location and the difference is the marks on the outer rings of the balancers. That's why i was thinking if you used eveything from the later engine you'd be good. It may very well come down to checking absolute TDC with a piston stop as 67Dart273 spoke of.