I was doing some reading online and stumbled upon this article from Auto Geek
The highlight is using Meguiars Mirror Glaze #7 after a thorough wash and clay. I washed and clayed the drivers side and did a single heavy application and let it sit for 15 minutes and removed it with another clean microfiber cloth. Here are the results and some notes afterwards.
As you can see the paint is taking the Mirror Glaze very well.
Rear door prior to treatment.
The paint is in decent condition for being 36 years old but its not without flaws. I discovered paint drips on the lower portion of the drivers door and the paint looks like it was applied with a brush or roller. But the rest looks fine.
I need to do the rest of the car and put a coat of wax over the mirror glaze since the glaze is water soluble.
I have a new valve cover gasket and filters so expect a post on valve adjustments and swapping filters possibly tomorrow or this weekend. Tomorrow I do know I need to adjust the belt to the AC compressor on the sanden conversion on our other W123.