I'm planning on building something similar here in the next year or two if I can get the right parts and a place to work....
I've been wanting to build two actually... A badass On road shifter with a Salvage Gixxer1K or Maybe like a ZX10R motor... Hell yeah and a full cage... and proper seat and harness... Then hit a tight canyon and scare the hell out the local Sportbike guys... Build it right, keep it under 500lbs or so.... Man what a machine...
The other, I want to take a Big Twin, with alot of torque... and build me a sweet little Offroad Machine... Some thing with a good 30" of wheel travel but just go kart sized... ya know? Something with a low CG, good torque, 4 wheels drive, and good ground clearance. Maybe a BMW Boxer motor, or Rocket III triple....