Well, I got the parts back today and fitted them with no bother.
I have to say it's better than I'd hoped. The buzz is gone completely, it's quieter, smoother and has a quicker lock time.
I've just done that thing with the pellet on the scope turret and it doesn't move so the recoil is reduced.
I couldn't be happier and would recommend Nick's services to anyone. It's made a very good gun a lot better and I'd like to thank Nick for the fast turnaround.
Chris