I agree with PJ. In the long run, attending Jim's class can save you far more money than it costs. I bought Recreating the American Longrifle at a muzzleloader match in 1995, read most of it, and decided I could build my own.
My first build was a Track of the Wolf 45 caliber southern mountain rifle in 1996. It's very accurate and comfortable to shoot but the stock isn't near as slim as it should be. Luckily the barrel fit in the stock without any problem. Unfortunately the gunsmith I hired to install the sights cut the front dovetail about an inch too far forward and the rear dovetail about four inches too far back. I didn't know where the sights should be but I expected him to know since he had "built" several muzzle loaders using Green Mountain barrels, Pecatonia stocks, and Thompson Center Renegade kit parts. I had to move the rear sight forward twice before I got it where I could see it well.
My next build was a 50 caliber Jim Chambers Lancaster. I bought Jim Turpin's cd and watched it several times before starting the build and luckily it turned out pretty good considering I could not make myself slim it down enough.
With two builds under my belt I decided my wife deserved a better rifle than the Jukar she had been shooting for several years. She and I went to Jim Chambers shop, met Barbie, and let them decide which rifle best fit her while I drooled over Jim's rifles. They decided on a 45 caliber York with a $50 stock upgrade. With the parts in hand I jumped in with both feet.
To make a very long story short I worked on that kit for well over a year before mangling that beautiful piece of wood a making it unsalvageable. Along the way I bought Peter Alexander's book, RCA 1&2, and several other books. I was long on confidence but short on knowledge and ability.
I ordered a new stock and while waiting for it I discovered Bama's gun building classes. I decided it wound probably be less expensive to learn the proper way to build than to continue doing it my way so I signed up. That was a very good decision. I discovered several things I was doing was wrong because I misunderstood what I had read.
I'm close to finally finishing Vicki's rifle. She had never shot a flintlock before this one but has put about a hundred shots through it while determining where she wanted the rear sight.
I strongly recommend Bama's class. You will learn how to properly build a muzzle loader and which tools are essential for doing the job without destroying valuable parts. The next most important thing in my opinion is the opportunity to handle some original guns and be able to better understand what the authors of the gun building books were trying to get across.
Good luck with your build, however you decide to proceed.