Boy you arn't just a kidding. It appears there are all different kinds of alterations on these rifles.
As far as rear sights go, I've seen original MkI sights and MkIII sights still with windage adj and MkIII* no windage adj sights on these rifles. Apparently anything goes.
Speaking of which, A square 10, I notice what appears to be a screw hole for the barrel securing screw in the bottom of your stock just behind the band. My MkI forearm has that screw under the band. Did they alter the position of that screw on some MkI stocks as your stock doesn't appear to be a MkIII stock, Ray