budget 273 build

In my experience, you can run the high-compression 273 on 91 octane, with only dialing back the initial timing one or two degrees (I think I have it at 12 BTDC). There's a lot of quench area in the stock head.

Changing the subject, I think there's a lot to be said for the AFB and the stock Commando single-plane intake (other than its massive weight, that is). It basically incorporates 3/4 deep spacers (or ram tubes, if you will) for each carb throat -- you don't get that with aftermarket setups. It keeps the velocity up, and I think it contributes to its incredible responsiveness. Just a thought...