You can actually shoehorn a 25" display into most classic cabinets, it will just BARELY fit between the sides. Dedicated Neo Geo 4-slot cabinets have 25" displays, and they are the same size as most classics. Also, some classics were available with an optional 25" display from the factory (Galaxian for instance).
I would jump all over that one. $200 is always a good price for a working game. My best friend has a dedicated Robocop and I believe he paid $180 (plus auction fees, which puts it a bit over $200). But his only has the 19" display, and the sideart is totally missing. So yours seems like a good deal to me.
That is a perfect example of a good cabinet to Mame. It is a conversion already, it has a nice large display, and the price is decent. One request though. leave the artwork intact. It appears to have a nice marquee, bezel, and sideart. No reason to fix what isn't broken. Sure the marquee and bezel can just come off, but that sideart dies once it is removed.