I'd recommend .020 on the block side, .019 on the intake side of the heads. That way the heads are matched and you can use any intake. That will get you a little more compression and get the heads to seal to the block. Get the guides tightened up and a performance valve job from someone who knows what they are doing. Next a good set of rings, Speed pro file to fit. If you get new pistons, bore and hone with torque plates. The four barrel carb and intake, cam with a round 268 duration, valve springs to match a double roller timing chain, and a windage tray would be nice. Should be pretty sweet. All assuming you have a decent engine to start with. To be really cheap, gaskets and seals, do the heads, rings, rod bearings, cam stuff and carb and intake. Dual exhaust down the road...