As for crank interchange....the forged 273 cranks have the small converter register, so, that could be an issue with using the later converters. Either machine the hole larger, or, build a custom converter with the smaller button. If it's going into a manual trans car, you may need a conversion bushing (bearing actually) if the 273 crank doesn't have the final machine work done for the stock pilot bushing. An engine rebalance will be necessary too.