I personally don't do kits anymore, I did a couple many years ago and found out that building from scratch is the way top go.....http://bdarms.blogspot.com/
Something like Pecatonica isn't like a screw together deal. It takes skill and know-how and proper tools to come out with a good product. Finishing a lock in itself is an art. A properly finished lock is ridiculously consistent and reliable. I'd say 99% of the "knowledge" of flintlocks is BS and just completely wrong. I've restored and shot many originals oldest being late 1740's and build mine to be that same standard.
With that said, for your first, something in the white is much better to start with like Caywood does. If you are going to go kit, Dunlap woodcraft or Chambers flintlocks is where I'd suggest.
This pic is of my turkey gun, 20ga choked-