Not familiar with that book, but saw a copy on ebay so have bought it and look forward to reading it.
In our rebuild, we used the remains of the original wheels as a guide and pretty much made it up as we went along - reinventing the wheel as the saying goes. The wheels were undoubtedly the most trying part of the rebuild. All four are now finished - the second two being so much easier than the first two, having gained experience and put the cursing and swearing behind us.
Photos of log wagons indicate that the designs were very varied. Again we used the remains of the old wagon, and a bit of intuition as a guide for how we think this particular wagon looked. Most of the iron work has survived, and this usefully constrains the look of much of the rebuild.
We had hoped to have finished it by now, but current restrictions limit what we can do. Plan to finish by next summer now, rebuilding on a very adhoc basis.
Another task is to see if we can get any shire horse owners on board this project.