Im with Eric on this. I know nothing is more frustrating than someone telling you to build something different than you intend but that is the rational decision. If you are saving money on the heads, take that money and look at competition products or ebay's 496 rotating assemblies. There some forged piston (18cc) kits that are $1150. You need to move that heavy car and those heads will work well with a 496 and a hyd roller in the high 240's to mid 250's duration. Im not as experienced as some of these guys but i have built a few 454/468 engines.