I have a 1992 KX125 worked to the nuts, agree, fun, FAST, agile/light and snappy bikes.
And my bike RIPS, I am 6' 1", 200lbs, etc...
As far as running it in a quad, its hit or miss. Hell, people have put highly worked 80/85cc motors in blasters, but these are usually for the youth classes, etc, much less weight and what not. (90lb riders, 19-18" tires, etc)
I would say no, just doesn't have the low end torque to not be BEATING it just to keep it moving. Now, a KX250, or any MX 250 at that, big difference.
Just my $.02...