In "Behold, the Longrifle", there is a signed and dated 1817 Stoffil Smith rifle that shows top-down, and you can see the cheekpiece sticks out a little more in the front than the rear, but not nearly as prominently as those on 104 and the exhibit guns.
I think the carving on the Smith guns is in line with others of the Eastern and Northern Berks county areas (assuming that's where he was, he apparently has not been reliably located yet??? Windsor township? which is the north end of the county). That style of work is seen in guns like RCA 65, and other "Bucks county-ish" guns, which I am inclined to believe are also made in Berks county. The carving on 84 I think is well within the carving range for this region, but it's also not quite like Stoffil Smith, or RCA 65 either.