The issue last I knew was, Mike B doesn't have the faceplates anymore. But, maybe there's another way...I'd call Mesa M-Th and ask to speak to service. They'll give you an answer.
I've had 3 B Coliseums, and 1 HRG B and they are all killer in their own way. They have a cool vintage vibe; like playing an old Fender that's been modded for more gain. If I were to choose between a 2B and a III, the 2B wins hands down for that vintage thing. But, like all Mesas it really depends on which preamp board you get in the B....The RP9C was the very last version before the 2C/C+ came out, and are very tight like a 2C and newer. Vs the earlier boards, which are looser but very vintage-y sounding like a 60s amp. Those earlier Bs are killer but need a slight bump to be tight.
I had a very early 2B Coli, and that thing was like a wild animal...no limiter knob, so vol was off-heart attack like a Plexi with a huge bright cap...my old drummer still mentions his hearing loss was from that 1 gig I brought that thing to. Lol