[blykins]

I've had experience with Procomp stuff.

A customer brought me a set of heads to use for a 383 SBC build. They ended up flowing the same as factory cast iron heads and to beat that, the valve cover holes were not in the right spot. They were offset towards the valves so that the valve covers rubbed the rocker arms.

I've got a few engine builder buddies that have tried their distributors, rocker arms, and intakes. The distributors died, one rocker arm failed and spit the roller tip out, and the intakes were porous.

Check the valve job on the heads, make sure the valves sit down against the seat and the valves are cut with angles that match the seats. I'd totally disassemble them and go through them.