If no overhang then I would run them. Hard to beat big blocks with $1000 heads with a smallblock thats cheap. What rocker gear pushrods and intake are you running to come in that cheap? Heads cost to much to get to 600 hp with a small block. But a 408 with iron ported late w-2 heads, cheap, would do you in for 5 grand. and the mains will stay in the block. Just having fun with you.