not sure on the flint to percussion conversion,
need a few better pics to be sure one way or the other,
missing wood at the lock,
split on the other side ,
hammer screw is a replacement ,
I would post these pics over on gunboards in the smoke pole section,
some good folks there, that know their stuff (unfortunately, one such wealth of knowledge passed last year)
the drop of the stock is a common trait on some of these rifles made in certain regions, those folks may be able to pinpoint that for you