There are grips that cover the backstrap which would increase the length of pull to the trigger. Helpful if you feel like you have too much trigger finger sticking through. There's the good old Pachmayr Compaq with an added pinky rest.
I went a road less travelled and ordered a Taurus (yes you heard me) small revolver grip and drilled 2 partial holes to fit the pin on a J frame. It added length of pull, didn't add to grip length (no pinky rest), covered the backstrap, and has a more rectangular feel rather than rounded which helps me index better and resists lateral movement. Feels kind of like a single stack pocket semi-auto. Best of all it was like 12 bucks.