There is only one Baryta in 60" I know of: Hahnemuhle Photo Rag Baryta. The others top out at 44 or 50".
There is also Platine (my choice) and a few others good ones in 60". But it's not a big selection compared to 44" media.
Platine is often out of stock in 60" for that matter.
There is also one 64" paper of the type you are after available, if you need those extra few inches
Be sure you get someone who knows what they are doing.
(PM me if you need more information, I'm in NYC but don't do printing for others really)