There is one thing you could try before chopping away wood from the buttstock.
I have successfully turned cheek busters into pleasant shooting rifles by bending the wrist to lower the drop at the comb. The process involves removing the lock, cutting a piece of 2 x 4 lumber to lay the barrel on flat with the board cut out for the sights (unsidedown) and clamping the rifle with C clamps to a straight flat bench. the wrist of the rifle is wrapped loosely with cloth shop towels secured with nylon tie straps, again loosely, heating Canola cooking oil on a hot plate until about 300 degrees, and pouring the hot oil over the cothes, soaking them with the hot oil, and keeping this up for about an hour. this will heat the wrist wood thoroughly. A wedge is made to insert under the butt's heel, marked first as the before mark, pushed in little by little to move the heel away from the bench, until you have increased the drop the desired amount, plus a little. The stock will have a memory and want to return to it's former shape a bit, but most of the deflection will remain once the wood is cold again. You can move the drop as much as you want, but I'd suggest starting with about 1/2" increase of drop. You can add more later if it isn't enough. On the two guns I did this to, a Centre Mark Tulle musket, and a Lebanon styled longrifle, the difference was profound. It did not effect the finish on the rifle either...no blistering, or discolouration. I should be able to post pictures (again) or send them to you via pm if you'd prefer. You could add cast off too at the same time, if that would help.
Taylor