Yeah, that's a great candidate.
You might have some trouble with the monitor sticking out the back, but you can modify the back board with a cut out, lots of games have those anyway.
You always have to be creative mounting monitors. You might have to build a shelf inside. I'd get that done before you do much else because you might put some holes in it. I bet you can even fit a 20" monitor in there.
It looks like you can just drill some more holes for buttons instead of building a new panel. But I don't think you can fit much of a trackball in there the way it's already set up. Maybe you can get a spinner.