That's a good looking repair, Doc. Short of having another stock on hand, I don't see how you could have done better.
I'm a rank amateur at this sort of thing, but I wonder if you could use some sort of epoxy in the crack and maybe put a staple or perhaps cut in a small biscuit under the buttplate.
As far as the finish goes, what if you were to finish a small area under the barrel and do the same to a scrap piece of the "new" wood, then compare the two. You could adjust the finish to get a closer match on the new wood. Again, I'm the farthest thing from an expert, just tossing out some ideas.
Well we don't rent pigs and I figure it's better to say it right out front because a man that does like to rent pigs is... he's hard to stop - Gus McCrae