Old parts are available from a variety of sources, but if the gun still works I wouldn't dream of trying to fix it before its time. I think you could use any cylinder that was produced up to about 1960; after that changes start to appear. If you do add a new cylinder assembly, a gunsmith might have to adjust the ratchet (or the existing hand in your lockwork) to make sure the new parts time right.
Those dents on the back of the cylinder indicate to me that there was previously a timing problem -- that's not necessarily dry-firing damage, though of course it could be. Maybe the gun needed a new hand, or hand spring. If it times correctly now, whatever was wrong with it was corrected in the past.
Those early postwar K-22s just go on forever. It's possible for them to get old and used-looking, but it is pretty difficult to ruin one short of hitting it with a hammer or using it to crack rocks.