Before you pull the motor out one thing you could try is to put 110 race fuel in the tank. Give it the timing it wants without worrying about detonation. See if the motor runs to your satisfaction fully tuned and no compromises on timing. Hopefully this will narrow things down a little. If the motor still doesn't run well then just lowering the compression probably isn't going to help much. it would be better to know this before you tear it down.