Decades ago, Bill Bagshaw (?) of "Pro parts" fame built a 440 in "Car Craft" that made 511 Hp, TRW pistons don't remember the number at the moment, MP 509 hydraulic, M1 single plane and 750 Holley, ported 906 heads with big valves, was a pump gas build. IMOP, I think the OP is gonna see his goal of 500hp with what he's got; just gonna have to buy ALOT of tires.........................