E-Bodies.org site is having a site recovery presently, so my links don't work.
There are a couple of good threads over there on restoration of plastic panels. Titles are:
"Repairing wasted door panels and textured plastic"
"Interior Plastic Restoration Journey"
Also this one.
The style that early E bodies and later B bodies had. That plastic that seems to dissolve over time. Lighter ones are worse? Has anyone tried to do this? What did you use?
board.moparts.org