The bends are not very severe, so heating probably wouldn't be needed.
If you go this route you will miss out on the shear joy and appreciation of the the wrinkled, ever-changing, misfitting, original cardboard headliner, and all of your closest friends will ridicule you for having a non-original, pretty boy truck... or not, as I don't know your closest friends. Your marginal friends will surely ridicule you.
I am planning on purchasing the cardboard one and trace it on some cardboard stock, but making it over-sized in the trouble areas on my recently installed misfitting one.
I have wondered if GM steam-pressed these cardboard panels into proper shape prior to installation. I cannot imagine some poor sap on the assembly line fighting with the same flat panels which we fight with. The cardboard firewall panels are clearly pressed (maybe steam) into shape prior to assembly.
Carl
