Archived from groups: rec.games.video.classic (More info?)
I'm afraid I can't help you with your question, but perhaps I can
suggest a good starting place. Try wandering over to another newsgroup:
rec.games.video.arcade.collecting - those guys really know their stuff.
BTW, I do know that there has been a hack for Ms. Pac-Man to accelerate
it, an alternate ROM set for Tempest (different set of levels), and a
board to combine both the Star Wars Arcade and Empire Strike Back
arcade ROMs in a single machine.