Between the receiver sight holes are the numbers 0774, which I think means it was made in July 1974.

Yes the rear sight is sweated on, there are no mounting screws. Front same. There is no front recoil lug on the barrel. The stock on my 9.3 x 62 is a later one with the square cut out in the
front end for a square recoil lug on the barrel.

This has the inside the trigger guard magazine release. The later Whitworths have sort of a transverse button on the t/g to release it and the stock is relieved to accomodate the button.

The 9.3 stock has that relief cut.