I am left eye dominant but right handed. I learned to shoot long guns left handed before I was 10 years old. When I took up bow hunting I didn't even consider a right handed bow. I suspect a shotgun buttstock specifically cut for a left handed shooter would be preferable to a modified right handed stock. Now I use synthetic stocks and I suspect they are "straight" rather than favoring right or left handed shooters.
NRA Life Member - RMEF Life Member - Vietnam Vet