Aluminum Eddie heads

With exhaust manifolds in use? I don't know.

The static compression ratio does not increase with the RPM's.
The dynamic compression ratio can increase with RPM's. it will have to be the cams fault (if you will) that the ratio increases due to the ramming effect of the higher engine speeds. This happens anyway though a proper cam can add more and fuel into the cyclinder.

Do not enter this into the equation when it comes to fuel and power figures. There are to many variables for your head to sort through. This is what dyno's are for. The only thing you are concerned about, and this is nothing more than a tried and true method, is for you to use the K.I.S.S. method. Keep It Simple Silly.

As a general base line, we know that 87 octane can support a 8.5-1 ratio engine no problem. Adding performance parts change nothing if the ratio has not changed or the cam remains the same or very close to stock. It does allow for more a effective air pump to operate and more air and fuel in and out which is why power increases.

Adding a aluminum head changes little. We know that it has the ability to disparate heat faster. I do no and can not subscribe to this as cooling the engine in any way shape or form.
Also, it can allow for a slightly higher comp ratio. This is approx. 1pt higher. This is a base line in the KISS method.

Due to the way aluminum acts on a engine, you can go up that 1pt. without a change in fuel grade.

Changing the cam can lower dynamic ratios in the low RPM range due to the design of the cam which will bleed off some compression. This is why a milling of the heads or piston replacement comes into play.

Sorry, I was on the phone typing out a bit more reply when things went berserk.