Back to the topic:
I built a very healthy 450-460 HP 331 based on a seasoned 71 302 Block, 10.5 SCAT kit, AFR 185 heads, Howards Cams Cam (Contact me for the spec), plus other good parts. Runs like a bear! Bought all the Heavy Duty AFR head parts, as I have hurt lesser heads. I keep the revs to 6K max, as the cam is from 2500-5500, and is all I need in a 2350 Lb Replica Cobra track car.
Avoid the Motorsports blocks. They crack, and crack everywhere when run hard. When mine exploded (yes, it did), it tried to seize the front crank journal, snapped the crank at #2, and sent the first throw out the front of the block. The remnants of the block was split down the center of the lifter galley, both sides at the bottom of the skirt, and between cam & crank journals. It was almost comical during teardown of the remnants.
Dan