Of course you can paint on top or try to restore. I have done it multiple times with excellent results.

Best is to do the following:

- Clean thoroughly the old paint to provide the right color and some bite for the new colors.
- Use chemically neutral colors such as Acrylic (I use them all the time for cabinet and playfield repairs).
- As mentioned, use the clear overhead transparent sheet technique to see if you color matches.
- Paint carefully small sections or use an airbrush for larger areas.
- I like to clear coat the whole thing with Polycrylic and a foam applicator.

You can see two machines I restored using that technique:

https://pinside.com/pinball/forum/topic/ycv-gottlieb-buck-rogers-restoration-or-the-infamous-system-1

https://pinside.com/pinball/forum/topic/ycv-recel-lady-luck-restoration-my-first-em

Good luck.
Yves