Nice site! Ms Nakamura has done her homework.
I own several Zorkis, including a couple of the 4K models and they are nice cameras if they have been properly maintained. Of the various FSU rangefinders, for picture taking, I personally prefer the FED 2 types b through d. These FED models have a 61mm rangefinder base. The later FED models (FED 2e, FED3,4 and 5) have the short rangefinder base.