Hi, I'm in the same boat as you, The response people have told me and most likely what I will be doing is litterally putting the engine in a box , shipping it to one of the site sponsors and have your credit card ready - I have looked into this option countless of times and spent hours online looking and pricing parts.
There are several ebay kits which offer the full rebuild whether it be back to stock or more power with a cheetah serval, cub, etc.
Regardless of how you go, It all counts on who assembles the motor for you. I would not rebuild it yourself. I have talked myself out of rebuilding it myself several times.
I will be going with a 4 mill cheetah serval setup, Long rod crankshaft trued + welded with max load CZ bearings , billet clutch with new clutch kit, serval cheetah cylinders, 35mm carbs, billet intake, v4 reeds, wiesco pistons 68mm, billet water impeller and billet impeller drive gear from mullen, K+N pod filters with outerwear's, and a couple other things I'm missing.
First off START WITH A CLYMERS MANUAL that was my first mistake.
What size are your cylinders at now??
You will get a lot of support from this site, but be warned these guys are brutal to noobs like you and me. They will be honest but upfront - so prepare for the mixed criticism, whatever you do good luck my friend.