Congrats on the purchase but it's my opinion that you're just wasting a cab for some PSX emulation that you can do with a computer and WS display OR a PS3 console with games bought from PSN that's hooked to a HDTV. I don't really understand your goal here
If anything you should simply make a dedicated MAME cab assuming everything in that still works or whatever doesn't work then get some working parts.
No other kind of emulation is more fun than MAME on a well designed cab IMO.