I still have the mk3 that I bought in 1976 and it’s as lovely now as it was back then, a mate had the airsporter and that was a great rifle too.
I must say, the rifle I lusted after back in the day was the origional mod 50, never could afford one.
If I see a nice example now I’d snap it up, same goes for an fwb300.
Good luck with your new purchase.

Kev