Sarf.

Yes I think it is a Maxigrip rail on the Superstar.
As far as I know the mounts would be the same as
for any other parallel rail! about 11mm!
I expect I have a set of scope mounts to fit!

Its only the early Airsporters that need the 16mm (5/8")
rim fire mounts, and then you have to modify them
to suit the curve of the action.

Weaver mounts are 20mm, I have loads of them if anyone
wants a set.

Mike.