Advancing or retarding the cam has more to do with torque and horsepower readings on the dyno than compression pressure. Basically, advancing the cam increases low-end torque and drops top end horsepower a little. Retarding the cam helps HP at the expense of a little bottom end. On long, fast tracks where the RPM could be kept on the high side, we would retard the cam a few degrees, usually no more than 4 or 5 degrees. Where we needed a good holeshot off the turns on a short track, we would do a 3 or 4 degree cam advance. For overall good street performance, I'd install it straight up.
Retarding the cam eats up piston/valve clearance in a hurry, as the piston tries to catch up to the exhaust valve as it's closing. On a stovebolt with the deep-set exhaust, that won't be a problem. One very radical roller cam we ran on a 350 engine had the closest piston/valve clearance at 15 degrees AFTER top dead center- - - -the intake valve was accelerating faster than the piston for the first few degrees after TDC. I doubt if you'll encounter that problem on anything you can drive on the street!
Jerry
