Having worked with a good friend who lost the vision in his right eye, and previously had a pace-maker installed in his left chest, he first tried an off-set front bead, and he found he could shoot well on clays, he could not hit wild birds; he just could not line up the sight and still look at the bird. My friend could not change over to shoot left handed due to his pace-maker in his left shoulder. I worked with him and made three cross-over stocks, first an 870 Remington pump to kind of "test the water", and finding it worked well for him, I made a cross-over stock for a Beretta 16 Ga. O/U, and finally for a Perazzi O/U 20 Ga. I do feel that if one can, one should change over and shoot from the opposite shoulder. But not all people can due this I guess. The problem is if you need a cross-over, you are limited to guns you can shoot. I do know of one very talented shooter who switched to left handed shooting when it was discover he had a left master eye when he was in his early teens, an he was always someone you had to beat at trap and Olympic bunker shoots.
It is not easy to make a cross-over stock and fit it to the shooter. Here, fitting it the key element.