That's not correct. Until 2008, 11x14 HP5 Plus was stock, but FP4 Plus wasn't, and had to be ordered through the annual "ULF" program. Starting in 2008, both emulsions became available only through the annual program. See page 3 of this document:
Originally Posted by Rob Skeoch
However, some distributors in some countries may order extra film during the annual program, or may have had HP5 Plus left over from when it was a stock item. In those cases, the 11x14 film would continue to be available to dealers unless/until the distributor runs out.
shows 11x14 HP5 in stock.
Nick, the OP, said "I print in platinum and would prefer to steer clear of the HP5."
Originally Posted by Don12x20
Nick, if you don't mind answering, why do you not like HP5 and do like FP4? I print silver and don't know what may be wrong with HP5 for you. I know there was a UV filter problem with T Max 100 and not 400. What is the problem with HP5?
You might try bigcameraworkshops.com. They sell film for l.f. cameras as well as l.f. cameras, lenses. etc.
We have 3 boxes of 11x14 HP5+ in our freezers right now. Call if you want to order it.
Howard Efner has published development times and resultant densities of HP5+ using DK-50 and D-19 on the Bostick & Sullivan Carbon Forum You'll find that the densities he achieves with those developers are in the range for good carbon printing.