First, I appreciate that you want to do a project with the woodworking skills, and I can only say for the work and effort you are likely better off spending the time on a new rifle.
I have a Traditions kentucky with a 2 piece stock that I built from a kit. it was $225 when I bought the kit and I bought it as an entry level way of participating in a Morgan's Riflemen group impression. I've gone back and forth over restocking it with a one piece stock in a nice chunk of walnut, just to make it more "correct looking". After considering the cost/effort to replace the stock, I then considered replacing the lock, turning the octogon barrel down on the forward end, and the other hardware necessary, i decided long term it was better, and more cost effective to just build a new rifle.
In the end, I accepted my traditions rifle for what it is, a non authentic, but accurate shooting, reliable flinter and I am spending my efforts elsewhere. it will be used as a loaner for those starting out with nothing.
I have also seen used examples that are much closer to what I envision in the $400-$500 range which is what you will have in it when you are done anyway (if not more).
mP