Pete,I looked hard at this kit for my first real flintlock. I think ideal for you in .54. (lighter barrel)Made one for my son in .54 with a 38" barrel, and it feels a Lot shorter and lighter than it is. (Not a chambers kit though)I don't think you'll be sorry about your choice.Richard.
All my flints are 38" 'cept for a .45 which is 36". Three of the rifles carry swamped barrels and are delightful. My favorite is a .50 and sort of a "fantasy" rifle. "B" wgt rb Rice barrel and 12.5 lop. Very, very light and handy with a 38" tube. It would be called a "youth's" rifle, I suppose.
Pete and all,I did put the above gun of forum a while ago. Think you saw it, but it's here if you want to look;http://americanlongrifles.org/forum/index.php?topic=46458.0