There are several surviving John Bull rifles with captured lid boxes. The Isaac Guess rifle is one, and the famous "Charlotte Anne" rifle is another, which looks to be where you to the inspiration for your captured lid. I have also seen several other East Tennessee guns with captured lid boxes, including a wonderful one by Edward Reed that has a banana shaped lid, set in a captured lid surround.
That being said, if you are keepiing it simple -no silver inlays or key escutcheons etc., then I would go with one of your two simpler boxes. Or, if it were me, I really like some of the Elisha Bull styles in Jerry's books - sort of a melding of the "egg" and the banana - sort of like a wide, blunt end version with 3 screws in the finial. Some of them even had mixed hardware - iron guards and buttplates with brass boxes and ramrod pipes.
There is a big range of architecture on guns made throughout the southern Appalachians. Especially with early pieces it is often hard to tell exactly where they were made, especially with gunmakers who tended to move around a lot.
I really like the rifle Brian. Nice work.