This is how my interior looked like originally, except the sun visors and the armrests.
The old panels where actually not in such a bad condition. Had I had the possibility to restore with a nice green gray cloth interior these could have been cleaned up.
The door panels were renewed and covered with a leather skin and the chrome lists attached as on a car with cloth interior. There shouldn't be a waffled intermediate part as I had in my original interior. Had my door panel had a decorative seam/baseboard/socle at the bottom that should have been in the same way but made in leather.
The armrests were taken apart, bakelite polished and the base for the leather was repaired with spray foam which is easy to form. When redoing the armrest leather they hung moist leather over the "foam", attached weights and by doing so formed the leather perfectly after the base.