I'd say, if you got the tools, time and most importantly gusto, build your own. It'll be exactly the way you want, with all the features you want.
If you're looking for something quicker though, and have access to an old cab, then convert it. There are rules though for converting cabs to MAME machines.
I believe there is a link on here somewhere.
There's even a point though where Pac-Man cabinets are so totally unsalvagable, that the best way you can honor it is to make it a MAME box. But what you're looking for are either: A newer, "generic" jamma style cabinet in good condition; or an older classic style cabinet in wretched condition (missing all parts and destroyed sideart are almost a must).
There are some purists though who will remind us of an important fact though...
"That Mortal Kombat / Street Fighter 2 cabinet you're about to take the jigsaw to, in 20 years WILL be as valuable as a Pac Man cabinet is now. You sure you really want to do that?"
You really think there's going to be any arcade machines left in another 20 years? Sad but true.