"B" appeared on the DCDR as part of the deal to acquire GSWR No. 90, though the aim was always that she would be ideal for off-peak trains like, say, midweek, New Year's Day, or visiting small groups or school parties.
I applied for funding for the then £160,000 stg required to fully restore her. Luckily, as fate would turn out, this was declined; had the funds been made available she was headed for Rail Restorations North East in England, the very firm which went bust when 171 was there!
She could have ended up being siezed for scrap over there!
Thankfully she survived.
Further attempts to find funding for her after that have not yet been fruitful. It may be assumed that today £200k woukd be what's required. I hope it happens some day.
6111 as a push pull vehicle with C231, plus SLNCR "B", would make a nice duo there. Subject to suitable funding all is feasible - but for the pair you're looking at half a million sterling, and with the north brexiting out of EU funding, it might take a while!
Incidentally, over the last thirty years, the sums of money which have flowed into Whitehead and Downpatrick from Brussels have been such that the survival of the former was greatly enhanced if not saved; of the latter I can state with certainty it would not have survived....
But that's another story!