Small block intake

Right on with Rumble’s input. On this application even the later Factory QuadraJet Is good. The performer has the last inch or so of the ports at the flange necked down to a 318 size port. Port match the floor and walls to a 1/16 or so of the intake ports in the head. Leave the roof alone to keep velocity up, the overhang acts a reversion dam.
The dual exhaust and crossover or X pipe will definitely help. If you’ve got the room, a set of early Magnum 2-1/4 inch exit exhaust manifolds would be an excellent addition.
Instead of a cam swap, put a fresh timing set in and advance your cam four degrees. The stock specs are .410 252 duration and 109 LSA, and advancing it’s worth some extra cranking compression and low end response. But if you decided to swap cams, make it worth the trouble with this cam and complete K-Kit. Lunati Voodoo Cam and Lifter Kits 10200700LK