the bmw is a nice bike. but....
Your busa already has a nice start to it. You are going to lose alot of money selling the busa, buying the bmw, and doing all of the modifications to it. Spend half the money you will getting the bmw and building it on your busa. Much faster and nicer bike for alot less money.
You will get less then $10,000 for your busa and spend well over $20,000 on buying and moding the bmw. retail on all of the stuff done to that bmw is over $10,000 not includeing labor, plus $15,000 or so for the bike is $25,000 as that bmw sits. hell.... you can by a prett nice used prostreet busa that is capable of runing really low 7's and close to 200mph for the price of building that bmw with a stock motor.
if money doesn't matter and you want to buy and build a bmw just to be different then go for it.