91 engine to 06 bike. Remove left side cover of 91 engine and replace with charging system and side cover of 06. Use 06 carb.
So now you have 91 engine (with 06 side cover) with kick and electric start in the 06 bike, with the 06 charging and electrical systems, the updated 06 carb, plus the 06 has disk brakes as opposed to drum. Now for the 500 posts telling me what I forgot/got wrong.