putting a 383 in a 72 cuda
72 Cudas CAME as in FACTORY with B/ RB engines. Therefore it is a "bolt in."
You need the factory proper engine brackets, IE the metal bracket between the mount and the engine, and the matching (rubber) engine mounts for 383/ 400/ 440
Same with manifolds/ headers/ exhaust. All factory stuff for BB engines
You'll either have to upgrade the radiator or at least have the lower outlet switched side to side
I'm not absolutely sure, I think the rear crossmember is a go as is. Depending on what trans was in the car, you'll need a different driveshaft.
Minor wiring changes, off ya go.