Quote Originally Posted by Robert Kennedy
Aren't there converters for that?
There are 39mm to Leica M mount converters, and they are what I use to adapt the Russian/Ukrainian Rangefinder lenses to my Leicas. These adapters leave the lens distance from the film plane (back focus) unchanged.

Adapting a SLR lens to a rangefinder camera - and enable infinity focus at the same time, is a different problem. I'm not aware of an off-the-shelf adapter that solves this problem.

In this particular case, the 2.8/35mm Jupiter 12 rangefinder lens is an easy and inexpensive solution.