MSW's comments are true but they can be applied to any of the "kits" offered by TOTW, Pecatonica River or the other small suppliers of muzzleloader kits.
More to the point concerning the Hawken, Track of the Wolf's catalog says,
"...a Hawken rifle is not recommended for a first gun making project, unless you have machinist skills, or an experienced mentor to guide your work. This is a good third project. Assembly requires a knowledge of breech and lock geometry, the skilled use of inletting chisels to finish the pre-inlet stock, plus abrasives, stains and reagents for wood and metal finishing. You will need access to a sturdy drill press, to drill and tap the few screw holes..."
Another issue some may have with the Jim Bridger's Hawken is its weight and balance.
You may have noticed the TOTW kit comes with a 1 1/8" straight octagon barrel.
If you select this barrel instead of the much higher priced tapered barrel you will end up with a very heavy rifle. The barrel alone will weigh almost 8 1/2 pounds in .54 caliber and the finished gun will easily end up weighing over 12 pounds.
Even with a tapered barrel the Hawken rifles were very heavy guns, made for rough conditions.
Before you give up on your plans, if you want to think about a less expensive, lighter weight, a little easier to build rifle, consider the Leman rifles.
They were made in the early 1800's in both flintlock and percussion and in half stock and full stock versions.
The Leman's originally used low cost plain maple for their stocks, often with painted on stripes.
Going that route can save you money. Of course, the kits (from Pecatonica River) are also available in tiger stripe maple at a higher cost.
If you choose the 15/16" octagon X 36" length .54 cal barrel for a Leman, the barrel weight will be about 5 1/8 pounds.
Speaking of barrels, they usually come without the breech plug being installed or the sight (and underlug) dovetails being made.
Your getting basically a box of rough parts, remember?
I recommend the flintlock because they are easier to build but the Leman is offered in percussion as well.
Just something to think about.
While your thinking, don't forget to check out Pecatonica River's offerings. Often, their prices are less and they are perhaps the largest producer of pre-shaped muzzleloading rifle stocks.
http://www.longrifles-pr.com/