@Uriahs, almost all the kits offered for the building of a smooth bored guns will be a collection of parts.
Pecatonica, Caywood, Chambers, Clay Smith and some others are also reputable suppliers of kit parts. Pecatinica and Track of the Wolf are essentially similar kits with Pecatonica having a wider selection of styles.
Do you have any of the books on the building of muzzleloading guns? "The Gunsmith of Greenville County", the book from Dixon's or the book by Buchele, Aleander et al.?
Have you watched any of the assembly videos by Jim Kibler, Bill Raby, Mike Miller or some others?
What experience do you have with precision wood working and metal finishing? What tools do you have for the metal work. such as a drill press? What work benches and vises do you have for solidly holding your work? What chisels and carving tools do you have for shaping the stock and inletting side plates, locks, trigger guards, trigger plates and butt plates?