+1 Try the castings, but I wouldn't trust the valvetrain.
Premium components LOL, those heads cost 400 bucks for the pair bare for dealers, hmm 300 for valves, springs, locks, retainers, cups, and seals. OK. Love the small block chevy pis as well. Pass, find a used set for 700-900 bucks. Doesnt matter if the used heads need a little work. I guarantee those heads have garbage valvetrain