I've only had two of my motors with my iron heads on the dyno, one is the 9.5 452" with 452 heads and it made 520 hp and 545 ftlb torque, I was pleased with the numbers considering the compression ratio. The other is 500" 12.5 cr 915 heads that made 645 hp and 620 ftlb torque, I'm figuring that TF 240 heads would have gotten me 60 hp from the other builds I've seen on the same dyno.