383/build

By straight up, I'm guessing you mean you installed it 0* adv/ret dot-to-dot. Thing is, with COMP cams, they grind their bumpsticks (unless specifically requested, or otherwise stated) 4* advanced. So, as long as your timing set is dead on, you're actually installing it at a 106* ICL as opposed to the 110* ICL that the cam is actually supposed to be.

If you're running a steel shim head gasket with a .500"+ lift cam, and no valve reliefs, your pistons are probably in the hole a pretty good bit or your p/v is super close, but then again, I can't claim any familiarity with BBM build up. I know factory slugs, and factory replacements like KB Silvolites are as much as 0.080" in the hole based solely on what I've read-if not more.

Let's assume for the moment, your pistons are 0.050" the hole with no reliefs, an 0.019" head gasket that's 4.38" diameter (pretty standard), and 72cc combustion chambers, you're probably closer to 10:1. If you're < 0.020" in the hole, your CR would be closer to your original estimate if not possibly higher. But I'd think your valve clearance would be super close with .500" lift and no reliefs.

There's very likely someone in here that's done either a very similar build, or the exact same build before...hope they chime in.