i'm going to start rebuilding my 305 tbi in a couple weeks and i'm going to add a few things to bump up the power. not going to drop a 350 in it like every says i should do. i'm going to go with comp cam ***** thumper cam, bore .30 over on the cylinders, and rebuild the rest of it. what are the best heads for a 305 small block? i know the tbi heads completely suck and i cannot find any 305 vortec heads. what's the most displacement i can go on combustion chamber in the heads. is 64cc's too much?