Some people may disapprove of my methods but I want to share what all I did to mount this beast and my struggles.
Mounting width at bottom of the frame measured to 65mm, but top ones are slightly narrower.
Here's what 65mm looks like compared to the derbi width:
Derbi case is about 90mm wide.
Cut the top mounting holes off the frame
Cut the lower right boss off of the derbi motor. Keeping the left side to ensure chain alignment. I don't think I took a picture, but i heated up the bottom right frame mount and bent it outward 12mm.
Compressed the forks to check spark plug clearance
Decided that I had to move the motor mounts back 1" to clear the spark plug cap. Cut the stock welds carefully.
Got the mounts moved back and tacked on the frame. Also cut the top frame mount more and cut the frame away by the middle mounting hole.
Welded the motor mount fully, made a boxed front mount, and a new intake. Welds will be ground down before paint.
Threw the tank and seat back on. Still need to figure out an exhaust.