Let me give
@Crumptinite and
@Wraith some actual advice though, and I'm sure
@twistedsymphony would agree here:
"If the monitor is good, and the speakers are good, the rest of the cab is (usually) easy to replace."
Make sure when you test that cab, you test resolutions that you will commonly use (15khz and 31khz), and leave the monitor on for 45 minutes to see if the flyback acts up, its an MS2931 chassis after all. These were wired for Model 3s, so they include the Model 3 harness, and not the 001 Jamma loom. So be prepared to test using VGA. Naomi is a great system for testing because of the gray startup screen. It can really point out the burn-in.
Most of these will have some burn-in towards the bottom from the credits, and possibly a line up top from the stage select screen. Make sure you gauge how noticeable it is when checking it in both 15khz and 31khz. I've found people hide burn-in in 15khz, when 31khz points it out like a sore thumb. Keep that in mind because it's a stronger argument to come down in price.
Obviously you'd want to make sure you control panel isn't cracked and the marquee is ok blah blah.
There is some extra wiring for the Bass Fishing controls, but other than that its 1:1 a Blast City.
I personally wouldn't sweat the knee buster unless you're applying for the Blast City fashion show. Again, you can easily paint some flat top bolts white and you'd be groovy. It's always nice when 2p bashes his knee when he loses.