You send that rifle to McMillan and they will make you a good stock. I'd have them do the fitting as well since you'll probably have to send the barreled action in. You'll pay for it, but it will be the best composite stock you can get.
As far as differences between the A-Bolt I and II. The II has a chrome plated sear and adjustable trigger and as mentioned above, the bolt was redesigned. I do not believe the stocks are different as far as barreled action fit is concerned, although they did make style changes in the pistol grip and butt area. Browning lists the same part number for replacement stocks for both guns, so there is no difference in barreled action dimensions.
JM
