In case anyone else needs a step-by-step, here is how I did it:
I used the current footpeg bracket to trace and cut the upper mating line on a piece of 3/8" wood (larger than the estimated finished part) then I bolted the wood pieces to the frame,and bolted the lowered foot peg bracket in the desired location to see how it feels. (I ended up drilling a few holes until I got it right) Then with everything bolted in place, I sketched out on the wood the final shape trying to get a smooth transition from the frame to the new footpeg bracket location. At this point you might have to rotate the top of the footpeg bracket to get a good transition, just make sure the footpeg itself stays in the same place. I cut the final wood patterns to shape, then used them to mark the outlines and drill hole locations on the final drop plates.
I cut the plates out with a band saw then used a disc sander and file to smooth them out.
Hope this clears it up.