I have bought a Sauer 202 and now I am looking for good mounts for my Zeiss Conquest DL 3-12x50.

The shop offers the ISI mount (rings) which is very low and I think that is a good idea. However, in the Sauer cataloque there a two versions: -42 mm and 42-56 mm scope lens. Does anyone know if the 42 mm version ISI definitely will not fit a 50 mm lens?