Hi Ya Timberdog,
Welcome to ALR. As you have likely realized, this is a great site, especially for us novice builders. Your profile doesn't say what area you're from. If you are anywhere near central Kentucky, I urge you to come to the CLA Show this Friday and Saturday. Chambers, Dunlap and many other suppliers and builders will be there.
I put together my second long rifle from a Dunlap Isaac Haines "kit". It was good quality and I was happy with it, no problems with what they provided. I have a Chambers "kit" on the shelf that I haven't started on yet. It looks to be great stuff too.
Just my opinion, but Dunlap's main deal is wood, not just gun stocks, but lumber to all sorts of craftsmen. The Chambers' focus is flintlocks. Nothing against Dunlap, but knowing what I know now, Chamber's gets the nod.
Have you decided what style of flinter you want to build? If not, I would suggest studying originals in the various reference books (or come to the CLA Show) before you decide.