Yep, that's a Model B, and a cool one at that!!! I would say that the sight and scope were installed over here, popular modifications at the time. Although anyone 'GOOD' COULD HAVE installed the G&H mount like that, I highly suspect G&H did the work since its properly mounted with no bolt heads showing.
Way cool rifle! How about that oct-to-round barrel and rib??!! And that was a more or less standard rifle back then!! Nowadays, the factories can't make a decent, plain rifle and places like H&H, Purdy's and such charge $30K (US) to make a standard rifle the way it should be much less any actual 'custom' neat features!!!

Okay, okay, I'm going to take my meds, now!!!!