Hard to say since other things change when you change the heads. Most power I saw from the 240 heads on this engine with a Wilson ported intake was 727. So that is a roughly 50 hp increase but I also changed the oil pan, oil pump and added a vacuum pump since I ran the 240 heads. On the flip side, the 240 heads were run with a dry sump system which isn't a bad setup. Here is a full write up on the 240 vs. 270 shootout: Dyno Day: Trick Flow 270 Mopar Heads - Hot Rod Network
