Crank ends should be the same except earlier blocks had 7/16" fine thread holes for flywheel bolts and later cranks had 1/2" fine thread holes. Early cranks can be drilled and tapped for the larger bolts.

I would be interested in what you find if any differences. My 292 had a big honkin flywheel on it like it was in a bus or something and will be getting a flexplate for an automatic tranny in the near future - once I figure out what to get.