I was in the same boat a few weeks ago with the the front and rear 1150 GS ADV shocks for my rebuild project. NDM in North county can't /won't rebuild oem shocks. I contacted Lucas aka Denz0 about the shocks by PM and then on the phone to see what he was going to do . I sent the two of them over by post which cost 29.00 euro(15.00 euros postage, 14.00 insurance).
I got a PM from Lucas to say my front shock was fubarred and not repairable but he had a solution, that was to supply a 1200 shock which required modification. This was the first one he had done so was a test shock so to speak. This shock got a full service / rebuild as did the rear one and he upgraded the rear spring with a heavier one from his stock of leftover oem springs to match the front, sprayed the shock bodies etc and sent the whole lot back by courier for £250.00 which in my opinion is great value for money.
I have fitted the shocks to my daily runner to try them out and can definitely say there is a vast improvement in both shocks.
My advice would be to send it over to Denz0 you won't be disappointed.
Cheers
Dub 24