What else will fit on the frame

No cutting of either frames. The 490 was very simple. First I cut all stock mounts off. I used 3/4 by 3/4 inch square stock and made a "H" for the rear and front mounts. No pics, camera is a POS
 
i just sold a project blaster with an rm 250 motor in it, looked like the guy just reworked the mounts, just saw some pics here recently of sumthin big in one, with some frame cutting done and rewelded, its possible, those 350x motors were one of my fav's, my buddy had one while i had my 200x