I have plenty of welding experience & equipment, but very little skill with sheet metal shaping. The reason I find it surprising that no one offers the panel commercially is 1)In this part of the country, that spot is one of the first to see rust holes. 2)Inner and outer roof panels are produced and easily available. I couldn't imagine replacing the two roof panels and trying to "reuse" this little panel.
Same panel is also junk on the parts truck.

1959 Shortbed stepside 1/2 ton project
[Linked Image from i236.photobucket.com]
[Linked Image from i236.photobucket.com]