As JJ said, I don't know of any other source for good bezels.
I noticed that same sizing issue when I was putting together my UAII cabinet. I ended up going with the Betson 27" monitor, and the Happ curved screen bezel is plenty big for the UA2 cab. That obviously that won't help you though.
I'd do like JJ said, and find some black plastic to mount around the enges of the bezel.
Other thing I'll say is that I didn't like the monitor mounted right up at the front of the cabinet and nearly vertical like you'd have to mount it to have the bezel attached to those little mounting strips you screw on. It felt both too close to the player and too vertical.
What I did was mount the monitor (using angle brackets and 2x4's bolted to the monitor frame rails) a couple inches deeper into the cabinet and tilted back maybe 15-20 degrees. I found that it makes for much more comfortable viewing. I haven't done it yet, but sooner or later I'm planning to mount clear plexiglass on those bezel mounting strips the UA2 comes with to keep peoples filthy fingers away from the tube.
If you go that route you'll need some extra of that black plastic. With the monitor and bezel tilted back a bit the top part of the bezel ends up behind the speaker shelf and the marquee light (I presume you'll be adding one) ends up shining down on the screen. Simple piece of black plastic took care of that.
Also, without the bezel mounted to those bezel strips you end up with a little light creeping around the edges of the bezel since it's more or less impossible to cut it so the edges fit 100% flush against the cabinet. I picked up a little roll of black foam weather stripping from Lowes and stuck it on the back side of the bezel sticking a mm or 2 past the edge to take care of that.