Headliner what to do

[Grit dog]

Wow, I'm amazed your fiberboard was still good. Mine was crumbling and falling apart. Ended up using it as a template, and covered it with layers of fiberglass, then covered the fiberglass with the headliner material

Prettty sure the roof of my truck was shaded by an overhead camper most of its life. Paint is not cooked on it and it required multiple attempts to scrub off years of black residue (from not being washed).
This would have also saved the headliner from getting cooked by the hot sheetmetal.
So I got a good roof and headliner in exchange for the typical truck camper smash marks in the front of the truck bed….lol