Tony Hilton showed up a year or two ago on the Bronica Yahoo!Group selling his Bronica collection. You might look at the list of items and see if it was in there, since he had some of the real rarities, but I don't recall that one. You might also find his contact info and ask if he knows whether the lens really existed.
I think it's a doubtful, because there is no 85/1.8 for any other 6x6 system. It would have to be a fairly large, heavy lens. To be sharp enough wide open, it would likely be a Planar type in that era, and Planars for 6x6 and larger formats don't tend to be faster than 2.8, and performance is already getting questionable at the widest aperture, so an 85/1.8 Planar for 6x6 from the late 1960s would probably have some serious field curvature.