If it's an original Ms. Pac, keep it looking like a Ms. Pac. If it's a conversion then go with whatever art work you feel like. (My personal opinion). Other than the JAMMA harness, you'll need an extra button for the fire button for things like Galaga, DK, etc.
I understand the lure of a multi game cab. I will let you know that if it is truely a Ms. Pac you can keep the original harness and get a Ms. Pac to JAMMA adapter and avoid having to do that wiring. Then if it ever gets converted back everything is still in place.
https://www.mikesarcade.com/cgi-bin/store.pl?sku=JAM2PAC