390 w/open chamber heads

A 4" I built 6 years ago has 596s and dished SRP pistons. The 3.94 bore choices are less but go with dished and set the compression by the chamber size and head gasket because you can use anything. 9.8:1 is fine with a cam in the 240° @ .050 range which is a small cam for these engines. That combo makes about 450hp, instant torque, and get's 17mpg with 3.23s and no overdrive. It also is done at 5500. You must run enough cam if you build compression into it and with open chambered heads you have nothing helping you. So go low static and at least 240° @ .050 and you're fine. You don;t need special rockers, solid cams, or anything else. I would hwoever recommend the RPM if you can use it with that AC. It is a much better intake and will make more torque and power on it.