The worst problem I'd worry about is whether a TV would work with the guns. Probably would. Don't some showcase-style cabinets use TVs and composite video?
Pit Fighter sucks. It wasn't that great in 1990 and it's even worse now. If you're set on an Atari fighter add
Primal Rage back to your cab. Judging from the serial #, it looks like that was what it was originally. The weird thing is that in the Primal Rage manual, it makes several mentions that the game PCB for the regular upright and showcase cab are different and are NOT interchangeable. It makes me wonder what was so different between them.
For gun games, Lethal Enforcers isn't bad, but I'd rather have something like Point Blank or Sharpshooter that has a bit more variety. Police trainer might be cool since you're adding the light.
I'd try to find games that have a good bit of variety. Maybe a fighter, a shooter, and a sports game. You've got a big enough panel you could easily have a 4-player layout even.
In some ways I wonder if running emulators might be better than running PCBs. The control panel is big enough to hold a 4-player setup plus a trackball. Multi-JAMMA setups are cool, but I'd worry about how to best utilize the space that this thing takes up. How much of the original wiring is left?
I'd also leave the speaker grills black.
Should be an interesting project.