Is that not 1”? Pretty sure any 1” scope will work. 25.4mm in an inch I think.
Edit: I could be way off base by the way
I believe you are right but this is a true German made scope with rings to match that I'm trying to replace. I believe that a common 1" diam scope would fit to loose in the rings. If I'm incorrect please somebody notify me of this
You could also lap the rings with a 1" bar, then use a 1" scope. That might not even be required. After further review, I have that all wrong. The above advise will do you no good if you have 26mm rings.