(beware, nerd math ahead!)
Width-wise the 16:9 26" LCD would be verrrry slightly larger (like an inch) than the 27" 4:3
For the same height as a 27" CRT in 16:9 LCD format, you would need a 33" screen. No problem, right? hehe

Only about 200-300 dollars (for a weird mysterious brand), but I'm absolutely certain that wouldn't fit in any standard sized upright cab. It would have to be a showcase. For a 16:10 LCD PC monitor it would only have to be 30" (Still not fitting plus way more expensive than a 16:9 TV)
I have a 26" LCD in my cab, and I like it. It fits perfectly in the Happ 16:9 bezel, and I think it looks great. I don't at all feel like it's too small.