Dedicated 25" Neo Geo cabs has a monitor that filled the cabinet, it looks fine.
Believe me, no one is going to notice the larger than stock monitor when you have a giant slikstick bolted onto a Data East cabinet that simply has no proper way to take the thing (thos slikstick panels only work looks wise on cabinets that came with control panels wider than the cabinet, basically, 1993 and newer cabinets.