Hmmmmm.....I LIKE the money is no object part!....
I would like a bike like Easy Riders second full suspension bike ( you can look him or just his posts up on this forum)....
Only changes I would make would be the engine....I would try for the factory 4 speed 50 CC engine OR Take the 9 HP version (Of course if I were really ambitious I'd opt for the liquid cooled 11 HP 50 CC engine)....
If I didn't get the Morini that had the factory gearbox, I'd try to make a setup like Sick Bike Parts Shifter Kit for that engine.
Of course everything else on the bike would have to be Top Notch state of the art....
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OK BUT for my more "realistic" bike....I would start with a used but not abused GT LTS bike (full suspension....Oh Yes....it DOES make a difference), stick in a "80" CC HT engine, Add Shifter Kit and Power Pipe...
Serious Fun at a reasonable price....Hardest part is to find the used GT bike BUT they do come up every now and again (I scored 2 of them off eBay in recent times).
Hope this helps you. Good Luck in your build.
Andrew