Rootsy,
You've pick a very good stock to begin from. As far as architecture, there's not a better stock than Chamber's. So, in that respect the architecture is already there. So trust Jim's start.
Where most beginners (myself included, and I've built well over 40 guns) the biggest mistake is usually, leaving too much wood.
The main areas for that sin, is the lock panels, wrist, and fore stock.
Most of the fore stock borders on original rifles is as low as 1/16" or less. The barrel pins hold the wood to the barrel, not the barrel to the wood.
The books you're talking about will help you in the shaping of these areas, whether the fore stock is triangular, or oval in shape, whether the wrist is taller than wide, etc, etc.
Your buttstock will already be basically shaped, and once it's taken down to the buttplate profile, you're pretty much where you need to be. But, it can already be slimmed a bit more.
Here's one I put together from one of Jim's kits a year or so ago. Like I said, maintain the over all architecture, and slim her down some, and you'll have a nice Early Lancaster to shoot for the rest of your life.
I can't tell you how many times, when I finished a gun, I realized I could have slimmed it down more.
Most of Haines work had 4 piece boxes, and some domed lids, There are a lot of good, pre-made options available out there. But if you want a wood box, put one on there.
Hope this helps. Good luck.
