In a word, DON'T!!! I've had several in the past, supposedly brought up to snuff by the American importer. Still plagued with problems: misaligned mirrors, light leaks, erratic shutters, etc. Possibly, if you can find one rebuilt by Arax, you might stand a chance of success, but they're no longer doing their conversions. It's a shame, since there were some great lenses made for them, especially if you find can some of the Zeiss Jena Pentacon lenses in P6 mount, usable on an Arax with the mount converted.
If I were to attempt another romp with a 6x6 FSU camera, I would consider a Pentacon Six/Praktisix, just for the lenses. And I do think the East German manufacturers of the Pentacon line maintained, post-war, as much as possible of that traditional German pride in craftsmanship. I've almost talked myself into a Praktisix on several occasions, since I have a number of their lenses that I use with adapters on my Pentax 645N. However, finding one in good condition, ideally CLA'd, has become difficult. All the ones I see online are from Germany, vastly overpriced, or Ukraine, which is no doubt fraught with delivery issues because of the war.
And of course, you can't fit a digital back on one of those, unless your "camera whisperer" is even more capable than I can imagine!
