Forget "shaving the head" you'll develop more problems, save the "mods" for a car... I learned long ago, that doing 1 performance mod, requires you do several more to make the first mod effective, (ie.) you add a bigger carb.. now you have to use a modified or better intake manifold, which means you should port & polish the cylinder head(s) .. then a cam with more lift & duration to get the larger amount of fuel through the cylinder head(s) which should have bigger valves, better springs, stronger rocker arms, etc., etc.. etc. etc.,, & modified exhaust so it can "breathe" out the larger amount of exhaust, which is done after a "hundred other things" .. might as well go ALL THE WAY ! empty that bank account, and shorten the life of that engine... leave the "hop-up" items to the guys with DEEP pockets......