47-55.1 Straightening front bed panel

[51 3600]

I took the front bed panel off my 51 3600 today. It's a 54 box btw. The panel is bellied out from years of people throwing 4x4s, fence posts, blocks, trees (you get the idea) into the bed. It's to the point where the bed panel rubs on the back of the cab.This will remain a patina truck so I just want to straighten the panel so it looks halfway decent and doesn't rub on the cab anymore. Were I to paint the truck I'd buy a new panel. I'm not a body man but I think I'm well beyond hammer and dolly work here. Have thought of laying it face up on the garage floor and jumping on it but figured I might get better suggestions from the knowledgeable here.