I have the same situation, arthritis inflammation in right rotator cuff plus a 1/2" long bone spur right in front of it just a bit offset from the joint. I am working on 80 years now, but still get to shoot some. Only last year I shot regularly once a week at least at sporting clays, generally just a single round of 100 birds. I shoot a Browning sporting clays 12 gauge with 32" barrels, fitted with a Graycoil unit that helps a good bit, also has an adjustable comb for a really good stock fit. If you really want lighter recoil, I suggest my second gun, for when the shoulder is really acting up: it's an older Rem 1100 with ported barrels, extended forcing cone, Kickeze pad, just about everything I could think of to help my shoulder last a bit longer. It is definitely easier recoiling, but I really enjoy the fit and feel of the Browning so much more, and my scores show I like it better. I still need a bit of a rub-down for that shoulder when I get home, but that's my story. I haven't found anything better, but maybe I just haven't looked hard enough yet.
