WCHA member Joe Staley had reproduced this (and nicely done) - I bought a copy at Canoecopia for six bucks... He's listed in the Wisconsin Builders Directory under Clearwater Canoeworks in case anyone wants to see if he's got any left...
There is a publication by Jay Parsons:
"The chippewa birch-bark canoe: A modern construction method"
He did this work while at Mankato State University. He did a very
good job and it contains very useful information. I recently got
a copy on loan from the University and photographed it but I can not
locate Jay Parsons to discuss hosting it or not. Anyone know him?
RE tump line length
Of course, these need to be adjusted for each carrier as they differ in head size, neck length, etc.
Adjustments can be made by sliding the tump knot inward or outward, though if the knot slides, it may move while portaging. Another option sometime used id to wrap the tump around the thwart. Again, this can rotate and loosen, but when wrapped provides more surface area & friction on the thwart.
Many modern day tumplines are nylon webbing, sometime with quick adjust ladder-type fittings.