Are all 273 V8's the same?

64-67 small register vs 68 & up large register.
Obviously large crank register will fit both and you can buy a bushing for the early convertor nose to larger register...or have early guts put into a later convertor case .
Never done that swap. Thanks for that info, it's good to know. I think I'll bookmark your post in case I need to find that info later.