Ouch! Is it a torn rotator cuff? I did that to my left shoulder several years ago and the best therapy for me was getting in the shop and using the vise. It was the exercise that truly helped!
My trail walk is still in place believe it or not and occasionally take a turn at it. Mary would like to see me host another now that she's retired.
I used a Colerain 58 ,1 1/8 dia. to build a Bridger hawken for a frequent cutomer this fall. Got it together and shot it at Club shoot in mid October. Didn't bench or any thing and first 3 shots at 25 yds OH were almost same hole shooting 80, 90, and 100 grains. The gun was about 11 pounds so it was steady for sure once I got it hefted.
I think the 38" D weight will be a perfect balance for you. My Jaeger lngth 54 is great for hunting but not muzzle heavy enough for any serious Flint target shooting. What lock are you going to use?
Ray