Do you know if it might be the same as the remote control for the Revox (Studer) A77? If so, then I have the diagram. Otherwise, I'll keep my eyes open for one.
Service manuals are available via anonymous FTP site at ftp.studer.ch
Unfortunately the B67 manual is some unholy creation - a 260MB PDF. But it should have sufficient data to work out the pinout from the recorder side, if it doesn't include the remote as well.