I Equalized combustion chambers on stock heads after pocket port and came up with 65.2 cc on each chamber, which is about 8.7 compression ratio.

If I mill the heads .020 I will have a compression ratio of about 9.05.

If I go .030 on the heads, the compression ratio will be the actual advertised compression ratio of 9.3.

With the price of gas and non-availability of 92 octane (at times) should I go with a 9.05 compression ratio and avoid detonation problems with low octane fuel, or go with a 9.3 and let the knock sensor take care of this problem when I have to use low octane fuel.

This is my daily driver.

 

Do you plan to keep the engine naturally aspirated? If so then go with 9.3:1. L98s (Fbody) came from the factory with similar figures and Ive never heard of anyone having to run premium to avoid knock. Keep the engine cool and be conserative on the ignition advance, and 9.3:1 should be no problem.