FWIW Warne lists their Maxima ringmount for 16 mm dovetail.
Another worth considering, which I have on my own Mod 1 (1947 vintage) is the Lynx ringmount. I have these on a few others too, including my ZKW465.They are steel, and I haven't had a moment's trouble with them. I'm not sure whether you can get them in the US, but there'd be a few Australian shops which would no doubt be happy to send you some.
