I used SEM paint on my door panels and all interior trim. I used whatever SEM adhesion promoter the local automotive paint shop sold for that purpose (can't remember the number.) The adhesion promoter I used did not cure well, and the finish paint over it in a test patch was very rough, so I stripped it off and just used the SEM paint alone. It turned out OK.
My door panels had a lot of scratches along the top of the driver's door panel. I assume the previous owner had a watch on his left wrist and drove "truck driver style" with the window down. I sanded down that area with wet sand paper and lost the texture of the surface, but that does not bother me. I am about to repaint the door panels so I will post the completed pics soon.
I did not want to spend the $$ for an OEM style panels for my 83 Silverado, and I did not like the original light tan (buckskin) color because it got dirty too easily. I had a local upholstery shop recover the door inserts with some leftover fabric I had from the stock style recover of the seat - I did have to cut pieces of threaded rod to replace the plastic threaded studs which broke off (that was an experience.) That plastic on the plastic door panel insert is super hard to tap - just chewed up the end of the tap - so they are held in mostly by a lot of wraps of teflon tape.
