The Missile 250R kits were cool but IMO the ruin of a great trike. If trikes were still produced I wouldn't feel the same about it.
I sure don't remember where but someone took a CRF450 and made a Fat Cat on steroids. I think he also done some others.
The biggest problem with the BW is the jackshaft adjustment or the jackshaft itself. I have seen when only a half link would get the chain adjusted correctly.
For thousands of years, riders were satisifed with one horsepower and they traveled the world.