Hi Bob,
Pedersoli makes a short land Brown Bess kit but it is not a very accurate copy. I don' t think they sell a kit for their Charleville, which also has some historical context issues. Track of the Wolf used to have a pretty good early pattern Bess. It could be made into a reasonable pattern 1730 that was upgraded (which they were) with stronger trigger guard and double bridled lock. You could make it into a passable pattern 1742. However, they don't seem to be selling it anymore. It appears that the only game in town for an historically accurate Bess or Charleville is the Rifle Shoppe. They sell complete component sets including stocks that are generally correct but they are not for the novice and you need to build the lock from cast parts if you ever want to get the components without a very long delay. For a Brown Bess (King's Pattern' musket) this video may help you figure things out.
dave