Get a plank if you are comfy working wood. Focus on
architecture, the rest is just the marriage of metal and wood and finishing in way. Specifically-get a "plank", but really a rough cut, stock
blank, from a professional longrifle stockwood supplier, to reduce issues with grain, density, and hidden flaws. Wood sourced otherwise may complicate things.
Architecture--all those large and small features of structure and execution that make the gun appear and function as one did from back in the day. Pull and drop and length are just linear measurement found in the architecture. Full-sized prints and mocking up a gun shaped object with scrap wood can help immensely here. Because I had no 3D reference in house, I glued a pair of 2x4's together and used a hoof rasp to make a long-rifle(ish) shape, then added (band clamped) metal along this "stock" to get feel/balance right. Used a nail for a trigger, the glue line becomes your centerline. This was the test-bed for pull, cast, etc. I didn't try to make lock panels or refined wrist, etc in this crude cobblage, but gained confidence that I wasn't messing up my first hunk of real stockwood.
Seeing and handling original guns is the ultimate teacher.
Also, most kits (you can usually delete their pre-carved stock (they can bring their own set of issues)) for anything "Southern" include a Germanic lock which offends
my notions of historically correct Southern arms. I much prefer to use English style locks and see them most often in original builds. Why that condition exists I'm not sure, but often the kit sellers will let you substitute parts. I never bought a kit-and it has been years since I looked at them but I doubt they've changed. Maybe it's a test.
This does not apply to the offerings of Jim Kibler (Happy B-day Jim), but then his kits are in a class of their own and a great option for those who don't have/need/want a shop full of tools and hands scarred with the gaining of knowledge.
Welcome to the forum, the knowledge is here and most of it is searchable (but that a huge amount of
pictorial info was killed by that photo-hosting site going commercial). Now we have on-site hosting and not have that issue going forward.
edited.