I worked a long time on this part, filing and sanding, looking for a perfect line up. The problem is, it bends in two directions while you're fitting it and you think you have it just right, then drill the rivet holes and find out you still have a gap at the bottom. Not thrilled with it.
Traced the outline of the lower skin on the fuselage and made the two brackets that it will rivet to. These only curve in one direction although it is more dramatic of a curve.