big block heads

$150 is high for 516s. But, with some basic porting, they'll make 500hp on a 440 with a hydraulic cam. Closed chamber, poor exh port, 1.6(IIRC) exh valve, and a flat intake port floor with a poor short turn. They are decent for getting compression up a little, but it takes some work to get them to really make power. Cleaned cores go for under $100.