Most everything will swap between them. You'll need a adapter to run the 2 pc. crank in the new block. Thats one option,drop the 396 crank in the 454 block and you get a 427. Use the older heads if they are decent castings and set up w/hard seats. Don't recall which head gaskets you need to use,but I'm sure all it takes is a call to any of the gasket companys to find out. If the 396 has the good 'truck' rods,they are the better of the factory 3/8 rods.Unless you happen to have a set of 7/16 laying around,thats all you need.
A good rebuild and properly picked 'standard' hot rod stuff and 550hp isn't hard to hit.

Doug