I've done a couple of flint Hawken rifles, some half-stocked, and some full. I would steer toward the full stocked rifle and keep it slim, with a Tennessee cheek piece and a straight long tang. Be sure to file draft along the length of the tang, and the end can be either rounded or spear shaped. A flint tang is appropriate, rather than a standing breech with a break-off, or hooked breech. I'll see if I can find a picture...