My MK2 cab has a 27" KT-2914F (the "Betson Multisync") in it. Fits just peachy with replacement "bracket boxes". I had to tilt it slightly when installing to get the frame of the monitor to pass by the supports for the front glass, but it fits fine once past those.
I didn't modify the cabinet any (no new holes or anything). Rather than move the existing brackets (the "boxes" made of folded sheet metal), I constructed new ones that put things in the right place for the 27".