there are plenty of generic 25" JAMMA cabinets that'll be decent for Galaga '88, though none will be a nice as the original. otherwise, i think maybe a converted Pac/Galaga cabinet would be pretty cool to do over as an '88, especially if you can get your hands on the artwork, and you can cram a 25" monitor in there vertically if you really want to (might have to be one with "side ears" for the frame instead of a universal mount.)
i just picked up a board as well and i'm having the same issue, though chances are good it'll just end up in a vertical multi-PCB cabinet with a switcher.