All the 300 pistons are the same from 98 to current I believe so as far as fitment goes, yes it will work. How much time does your new A cylinder have on it? Stock size is a 71.94MM and the B size is a 71.95MM, a very small bit larger. I would venture to say that the B would be fine. Just be careful to doublecheck piston to wall and ring end gap when you get the bike apart.