if you don't already have a copy, you should invest in The Gunsmith of Grenville County, or Recreating the American Longrifle. Both of these books can be had at Track of the Wolf, and although they appear pretty expensive, they'll save you more than their purchase price in parts you didn't ruin.
also, just so you know, a 'kit' is something of a misnomer: think more along the lines of 'collection of unfinished parts.' the construction of a decent looking rifle is going to be a bit more than the 'tab-a-into-slot-b' that some folks think it is.
I would encourage you to consider a pre- carved stock if this is your first build. (a "pre- carve" will still require a fair amount of work, but the barrel inlet will be done and the ramrod hole will be drilled) . Parts for an Isaac Haines can be had at Track of the Wolf, as well as Jim Chambers. not sure about other suppliers.
good luck with your build!