not so bad your idea - I thought at the first moment. It couldn't be 5 cm but maybe 1-1.5 cm. I think, this will not hinder the movement (maybe enlarge the armhole diameter same amount), so that it stays proportional). And then maybe 2 cm difference in the sleeve length will not be so noticeable.
Photo is a good idea, Terry. It gives better view to judge and with the mobile nowaday easily done.