A Trapdoor certainly is a fine hunting rifle. I finally got one just for that purpose, to hunt black bear...although I've wanted, and admired the Trapdoor Springfield rifle all my life. (the carbines have never been of much interest to me) But I find that the model 1873 Springfield rifle is pretty perfect just the way it is...although I'm not saying that a custom Trapdoor would not be a perfect hunting rifle either!
I've seen barreled actions, and just action and action parts for sale on the 'net, I've seen complete locks for sale at gun shows for what seems to be a reasonable price...have you thought about putting a rifle together from parts, rather than use a restorable rifle? My rifle may have been called a "junker" when I first got it, but it is now a very beautiful, accurate rifle.