If it helps, you can fit a 21" 4:3 into a taitorama but its close and the screen drops down below the CP and up into the marquee/speaker area.
You also need to decase the screen for clearance but it worked for me....
http://forum.arcadecontrols.com/index.php/topic,129835.msg1328236.html#msg1328236
Thanks for the heads up!
Approx how much did you have to drop the CP?
Maybe I'll go for a 19" 4:3 instead since they're much easier to come by.
The thing to do (I think) is to work out the angle you want your CP to lay at then reference everything else from that.
Once you know where the back of the CP will be you can then tweak the screen angle to be behind it then finally set the speaker panel angle from the screen if that makes sense?.
Whatever screen size you go for the screen bezel will be square so if you make a square board the same size as the internal width of your cab you can then play with all the angles.
On my set up when the screen is in a vert position there is no visible screen bezel but the top and bottom 4" of the "square" are behind the panels.
If you can find one a 21" looks mighty good - and it fits better than a 19" - just saying

.
The one bit of advice I will give is to put in a access door behind the screen, as I find it a pig to do anything behind mine just using the front door.
Good luck with the build!.