On a Regulation Tunic , the larger buttons are only down the front and the smaller buttons are only on the pockets.
It's not common but, I have seen original Tunics with only small pattern buttons used (down the front & for pocket flaps)...that could be a personal "fashion statement" though ..or maybe the guy was too cheap to buy the larger replacement buttons Roll Eyes.
You'd be a lot better off staying with the regulation style.