No offense - but I wouldn't listen to a guy who runs 12.5 CR untuned. And then a guy who would put 89 octane on a 12.5 CR setup.

You can "cheat" a bit by running a cam gear and doing some angle changes 1 or 2 degrees in either direction. But if you have a car to use as a DD wait until you can get a cam w/ with more lift and duration. You are actually above the limits of pump gas at 12.6 (untuned).