I have a 27" arcade monitor (KT-2914F) in my old MK2 cabinet.  It came without a monitor, and I happened to have the 27" laying around.  It fits, but BARELY.  I actually had to angle it in to get around some trim pieces that retain the front glass.  I also had to fabricate new mounts, but you could modify the original ones if you preferred.  It doesn't really look too big to me, but if you compare side-by-side to a normal Midway 25" cabinet, you'll note a distinct lack of bezel.