I will be starting a Xenon restoration real soon too. I spent three solid days sorting out issues with it and its finally all working. I am going to lightly mod it, including all LED (already done) and some other custom light mods.
Im luck that my cabinet is nearly perfect so I am going to leave it as is. The only real work on this one will be the playfield....this one is thrashed. I picked up a spare blank playfield on ebay that I will be installing all new inserts, an overlay and clear coat. After that I plan on practicing touch up with an air brush on the original and see if I can bring it back to life.
I only have one question. How can you not LED that back box? This machine looks simply amazing with led. Good luck with the restore!