I want to build a atc250r, but with a cr500 motor. How hard is this to do, what frame mods needed and stuff? Is this gonna be any good for mx use? I know I will have to use a extended swinger, but anything above +4 just isn't for me. I know some of you guys them, let me know what is invovled. I will plan on using inverted forks, possiblly modding the frame to use a no-link shock, short track setup, and how/what do I have to do for it o run somewhat cool?