Welcome LEWISJG95 to the forum.....
The kymco crank is pretty darn strong my friend. You won't need to swap out the crank. I turn 11,000rpm on the stock crank in my S9.
You actually have a better deals over there in the uk on parts.. The yasuni is a great, but very expensive pipe.. I would go for the technigas rs2 on a 70 kit.. I have the rs2 and love it......