I must still have the original sls springs in there as I didn't buy any others. I went for a quick fix at the time as I had a lot on. The garage who did the work just swapped the shocks but kept the old springs in. This would explain the sag of course. Unfortunately I disposed of the old sls shocks as I didn’t realise they have recondition value. So I will try the RA6028 springs with Ridex shocks and see how I get on. Will post some before and after pics for future ref.
Thanks again for your advice 👍