RE: Left eye dominant
I do everything right handed except being left eye dominat I shoot firearms and bows LH.
When younger my dad tried to train merh with a rifle b/c the limited option for lhguns but it felt unnatural for me so he quit trying. I have shot off my left shoulder/eye ever since. The only way I can shoot decently off the right sideis a patch over my left eye.
I suggest that you let your son deciede which feels better, if its right handed then he can be trained to use his weaker eye. If he's like me and lh just feels better, then let him shoot southpaw. Now a days the southpaw options for firearms and bows are better then when I was younger. Still limiting due to being a minority but most manufcaturers make LH models.