As someone who started this flintlock shooting and building journey some 40 years ago, here is my perspective. First, I live in Canada and do not have access to a whole lot of original rifles. I shot in a lot of matches, but back even 30 or 20 years ago the guns being used weren't really copies of anything you'd call an original school. Lots of Hawkens, and Pedersoli long rifles, CVA etc etc.
Books are great to learn from, but the Chambers or Kibler kits give you a nice starting point ie what the rifle or gun is supposed to look like. Great to learn from.