If it's any use to you, I have a Sussex Armoury AR7 (1979 or 80) .22 for sale, on behalf of a friend. Bought from the SA shop in Leigh-on-sea.

I have stripped it cleaned and re-lubed, replaced the spring and guide (still got the originals)

It has the original 'Single point' red-dot sight too, which works fine.

I suggested £250.