Initially I figured I would have to make the patch out of two pieces of steel and weld them in one at a time to make it look right. Then I figured why not take carboard and make the two pieces and then tape them together, lay it flat, tranfer the shape to some flat sheet metal, and then try and bend it into the shape I needed. If it turned out like crap I could always cut it and make the pieces individually. I was wasn't sure how it would go due to the 90 degree bend and two curves, but I was able to pull it off and I am pretty happy with the way it turned out.
After some fitment grinding it fits like a glove.
-Joel