This doesn't relate directly to 3rd gens, but I was hoping would could help me anyway. I'm helping someone build a 427 big block and was trying to find a set of used heads. I found what seems to be a nice cast iron set that have oval ports, 2.06/1.72 valves, and 113 cc chambers. I don't know the intake/exhaust runner size. Do you think these heads would flow enough to put out 450 horses on a 427 with 10:1 compression and around .550 cam lift?

 

They'll work... If I had the money I'd go ahead and have 2.19"/1.88" valves put in. A port and polish job wouldn't hurt either. 450 hp is easily achiveable with a 427, pretty much the same as getting 325-350 hp from a small block.