Mat,
I have to go along with Ed on this one being a parts gun and add that it is probably a little later than you are thinking due to the trigger guard and back action lock. I am looking at a double gun that was broken through the wrist area, as yours is, and instead of replacing the stock, it has a sheet copper wrap over the break, after it was refitted and glued. Parts gun or not, try to keep the original parts, as you received it, together. It will make a more interesting rifle and the new stock will cost you more, before you are done, than the rifle is worth.
Mark