Mark--
I've been involved in a similar search to yours and have discovered that, despite the seeming popularity of the subject at that scale, finding aftermarket decals is a next to impossible task.
Both Almark and Superscale had sheets out but both are also long out of production. I've been watching eBay and have seen a sheet for the XB and YB-52 versions on there, though this was about a month ago....haven't seen any others on there.
A couple other members posted in the thread I started on this topic with links they were suggesting....I'll find those and edit this post shortly!
John
***edit***
The suggestions I received included a link-- www.lhshop.nl
They had an Almark sheet available when the gentleman who posted it sent it...when I checked it I couldn't find it, but you may have better luck than I.
It was also suggested to try Hannant's search engine, or that I contact the manufacturer directly to request a different sheet. Unfortunately, Revell's USA website doesn't have a customer service type link available...not sure about their German one though.