Since there's nothing wrong with your bike, simply dial in better head squishband gap via a thinner base gasket set next rebuild. This will deliver a good portion of the boost and efficiency of head work.
SLP offers easy to install $45 carb wings. Improves the low speed jetting and adds hard acceleration if the reed block area is not so efficient.
http://www.slp.cc/catalog.cfm?pageID...&productID=644
Again, you'll have a whole new feel to your tired old bike with a hotter CDI.