I’m late joining the thread but.... I’m building my 70 GTX 440 4 barrel. It had 271 peg leg gears, and the original engine recently rebuilt with “flat top” pistons and no valve reliefs cut into them. Purple shaft .509 cam, factory intake, 906 heads and exhaust manifolds. It sounded good but, the power SUCKED!!!!! My winter project 2 years ago was replace the gears with 3:55 sure grip gears in its 8 3/4 rear, moser axles, 4 wheel disc brakes, firm feel suspension and sway bars. It was better power wise but not good. My 340 duster was MUCH quicker. Soooooo, this years winter project started as a simple intake and carb change (Edelbrock 800 carb and Edelbrock performer RPM intake. That has turned into pulling the heads as well and ordering TTI 1 7/8” headers. Well, it does have flat tops with no valve relief but.... they sit .115 in the hole!!!!! I’m pretty sold on the trick flow power port 240 heads and by my calculation prior to pulling the heads I though I’d have to run a pretty thick gasket just to get the CR down to around 10.5:1. That was my target CR any way. Now, I’m having to run a .036 gasket to get a measly 9:1 CR. I thought about pulling the motor and changing the slugs to some better slugs but time and my wife both say ENOUGH!!! So.... short story long, with my CR as it is, 9:1 the TF heads are 78 CC and the Eddy RPM heads are 75 CC and would bring the CR up to about 9.3:1. Would the CR be worth the lower flow numbers that the Eddy’s have or will the better flow and marginally less CR be better? It’s got 3 inch exhaust and an H pipe.