The FOV is capped at 97 iirc. Incidentally, there's also a SEPARATE cvar for setting True View (or w/e it's called) FOV. It's ALSO capped at 97.
My two cents about all this:
1. I think first person FOV and third person FOV should be two completely different cvars, and first person FOV should have a much higher cap, since third person with a lower cap is almost always going to give you a visibility advantage anyway over 1p with a higher cap.
2. I like the idea of a server setting that forces first person. It would definitely affect quite a lot about the tactics, cuz nobody would be able to cornerpeek and everyone would have a much more difficult time maintaining situational awareness (especially in very close-quarters situations). It would encourage different strategies. I would bet that saberists would be relatively worse, gunners would be more preferred. It would be really interesting. I'm definitely interested.
bonus third cent: I wish somehow that True View could show your own entire player model as translucent, since your own gun gets in the way most of the time.
bonus fourth cent: My keybinds include having scroll-up be First Person and scroll-down be Third Person. I strongly recommend this to anyone who wants to be able to very comfortably and quickly switch between the two, although I haven't actually used it much in practice, since I've adapted pretty heavily to aiming in third person with 0.6/0.6 cameradamp/targetdamp settings.