Edelbrock heads STOCK max out at 243 average on my bench. I can get them up to an honest 315 with a 2.08 valve and without moving the pushrod (tubing them and touching the tube) it takes LOTS of work and I flow every single port (and test air-speed) on the head multiple times to get it there. I bought a set of Harlan Sharp .350 off-set rockers but so far the little bit of tinkiering I've done the results have been disappointing. I will make it pay-off with testing sooner or later. The nice thing about the later style Speedmaster and ProMaxx heads is you can play with the floor more as there is more meat and less water passages.