i could get a real good deal on a 300ex that has a blowin motor and i could find a 400ex motor real cheap wonder how hard the swap would be im pretty mechanically inclined

 

i dont see why not, seen them before 300ex frame with 400ex engine. you can put anu engine you like into a wheeler frame! but as far as this swap i would safely say the most you would have to do is weld new motor mounts. i would do it if i where you!