A 383 using the 76 CC "smog" heads from the mid 1980's should come out with a static compression ratio somewhere in the 9:1 range or so. With a smooth combustion chamber that doesn't have a lot of hot spots, that's near the upper end of 'regular gas" compression. The effective compression pressure will depend on the cam grind, with a more radical cam resulting in a lower effective pressure due to the intake valve remaining open for part of the compression stroke. I have had very good luck with the Comp 268H cam in a warmed-over street engine. It pulls strong on a dyno run all the way to 7K RPM or so, with pretty good midrange torque. The idle is slightly choppy, but not enough to require a high idle speed.
Jerry
