You've been able to answer my Barnack questions in the past...thank you!
Yes, both are cammed correctly and in nice shape. Both will host either Elmar without issue. The III does rotate the focus witness mark (thanks for the term) slightly past 12:00, but focusses either perfectly.
Yes, it's a Jupiter 3 that fits and performs well on the II, but won't seem to even mount correctly on the III. Hmmm...thanks for the reply. A mystery.