KISS has LED built right into the CPU board. What they need is for Stern to dim them in software once a game is started. I have an aftermarket LED panel in my ACDC that does just that and it works great.
http://www.arcadeupkeep.com/ Use the dimming kit here for replacing the tube light in games before KISS...
One big thing is not to put bright LEDs in when replacing normal bulbs. Orbit retro LEDs are actually less bright than a 44 or 555 and help to cut the glare.