I believe that some models were made with an upward pointing lever and others with a downward pointing lever. If you have the ever-ready case that came with the camera you can usually tell because there will be a cut-out for the original configuration. My cases show that the lever direction was intentional.
I don't know for sure why they were made with these differences, but it may have had something to do with the focusing tab on some lenses colliding with the lever. Some early model Industar-26m's on Fed-2's have a focusing tab that makes them look like Jupiter-8's. This tab was omitted on later I-26 models, and may never have appeared on the Industar 61's that followed on the Fed-3's. Also, the collapsible lenses all had focusing tabs. I'm speculating of course, but the change in lever design may have been to allow for compatibility between older lenses and newer bodies.
-Paul