Nokona doesn't currently make a FBM over 12.5". You'd have to find a SBM100 (14") or N80 (13") in decent condition if you want to go with Nokona. They used to do a limited run of the SBM100 from time to time but I don't know if that's still the case.
Rawlings has the PRODCTJB (13") available. You'll find it highly recommended on here.
Vinci has several models available. The JBV04 (13") & the JBV-SB (13.5) are traditional FBM's. They also have regular glove options that are big enough to use at 1st base. They might be a good option if he ever has to move back to the OF: BR46 (14") & BV100 (15")
Glovesmith does the FB2 HC9 (13")
Kelley makes a couple of 13" models: ES 160 & GN 160
If you want to go the custom FBM route,
Capire will do up to 13" but the web is fixed.
44Pro will do up to 14" with a couple of different web options.
Dropping down to a 12.75" FBM significantly opens up your number of brands.......