if you find you have no problems with timing, leaks, fuel pressure, etc. that is causing your rich condition, and you think it may be from the octane (probably not, but I'm no engineer) increase your compression. you can shave the block and heads, run a domed piston, or blow it with a turbo or supercharger, get it up to 11, 12: 1 and you wont have a rich condition, or a lack of power!