Sharptails ARE grouse. If you mean you want to hunt both sharptail grouse and ruffed grouse, they are two VERY different birds. If you don't have a pointing dog, Sharptails are normally hunted with a 12 ga. and full or modified choke, and use #6 shot or even 5's especially in the late season. They are open country birds, and most shots are 35-45 yards. Young of the year can provide closer shots.
Ruffed grouse are close-cover birds, are smaller than sharptials, and most wingshooters ( as opposed to shooting them while they sit) would choose an open choked 20 ga with 7-1/2 shot. Shots are mostly under 30 yards. Target loads are adequate for them.
For your purposes, a gun with interchangeable chokes is most versatile, with a medium barrel length, 26" or 28" and can be 12/16/20 ga. Action type and gun fit are a personal thing.