Only 460hp

i think that if you want to go from 460 hp to 500 in a single step without touching the short-block, you need to up-grade to a street-roller. have a look at the xr series of comp cams. lifters are a pita to install though. you would need to grind the block for lifter installation. also, a switch to a single plane intake would be a good move while it is removed. if you want to change the pistons, srp has a 16.9 cc dish piston. going to a flat-top would mean too much compression ratio for the street. also, if i was you and wanted to switch heads, i would have your current ones flow-tested before making the move. they might be better than expected.