[blykins]

The typical Edelbrock head is 74cc out of the box. Pond heads are closer to 90.

I would not stack a big thick head gasket under the head just to decrease the compression ratio. If your piston is .xxx" in the hole and you stick a .060-.070" head gasket on it, then you butcher your quench distance.

I'm usually at 10-10.7:1 with aluminum heads and 93 octane. I've ran a tad over 11 without an issue.

If you're making a guess at what your compression ratio is, I would urge you to take some measurements so that you have a better handle on it.