Hello Snakebit, welcome to the ALR forum - loads of expert advice here - mine is not in that category except in a limited way but please read on.
Dave here, and I, a complete novice to rifle building but with furniture making experience, bought the Jim Chambers Lancaster "Kit" some months back. I say "Kit" in parentheses because it is more an assemblage of very well thought out period correct parts that come with a well made pre-carve stock. This is not a snap together deal as the term kit might imply, there is much work and consideration to do to complete a rifle. The pre-inletting of the Chambers Lancaster for the flintlock, lock panel, trigger plate and ramrod entry pipe are very close to finished dimension and care is needed to complete the job. The overall stock shape is nearly to finished dimension but requires wood removal also. Be prepared for some delicate work in those areas.
On my rifle I had to move the barrel back a bit over one eighth of an inch to align the touchhole and pan, and down a sixteenth for the same reason and to create a slimmer profile overall. This requires mostly using a scraper and flat chisels and is the first step involved in the build, next is the lock. The pre-carve for the flintlock panel is very very close and one must be careful not to enlarge it overly; the same with the other pre-inletted areas of the stock. Wood must be removed to move the lock in and seat the lock bolster properly to the barrel. The examples above are typical for the Chambers “kit.” If you feel capable of tackling wood and metal with chisels, scrapers, and files you are good to go. Completing a Chambers “kit” can be done if one is careful and proceeds thoughtfully. As I mentioned too there is a great deal of excellent advice available here on ALR. Be sure too to search the archives and tutorial sections for information, that is where I find most of the answers I seek for my build.
Good luck on your build.
dave