Guys I know everybody is different. But I've had the same 10/22 rifle and 870 shotgun since I was 12, maybe even before. I stand nearly 6'2" now and at no time, then or now, has shooting left-handed ever been a problem
for me with either. Lord knows my form and the positions I've shot in have been all over the charts since I was a kid.
Its funny the thing I hate most about shooting left-handed actually comes from SxS and O/U. After all these years those little levers on top never seem to learn. They must be pretty dumb