Congratulations on a really great gun!
If you can look past the breech pin and keep the forks well lubricated, the Supersport may be the best full power springgun BSA ever built. I've yet to get Superstars, Mercurys, Airsporters or pre-war under levers to shoot as accurate as my well set up Supersports.
DS prefix is a 1986 .22 Supersport according to the list on Knibbs' page.
I think 1986 may have been the first year of supersport production? Is it a Mk1 or a Mk2? Check the cocking links where they are mounted to the breech block, are there two or three links? The early Mk1 had two, and these may not be as durable as the later Mk2 with three links.
The sights come up for sale once in a while, so you should be able to find a replacement.