But it would be very interesting to see how long your thwarts are and where they are located on the canoe, because it seems that Jim Clearwater's IG is about 2" wider than mine. I'm thinking I'll end up measuring about 29" between the inner rails at the canoe's center, and about 31" at the beam (distance between the outer planking surfaces at the center).
Also, while you're at it, can you whip up some dimensions for your two seats.
So....the IG is way up and hard to reach.
Hole to hole the bow thwart position is 25 inches.
The stern thwart is 24 1/2 hole to hole.
The width of the hull, inside rail to rail (outside to outside) is 29 3/4. Yours should be pretty close to that.
For giggles I measured my Indian (15 foot) and that is just under 30 inches wide measuring inside (and not the rail caps).
The Brown hole to hole for both thwarts is 26 3/8. It is 30 1/4 wide inside rail to rail (outside to outside). It is 15 1/2 feet.
I have bits and pieces of seats. I have the original seats from an IG that I can lend you for patterns.
I also have a form for bending IG stems. You are welcome to borrow it. I also have an elm I am ready to cut for stem wood if you want to retain originality.
I'm keen on keeping original wood whenever possible. I will add some pictures of some porcupine damage on the Brown. Some of it I left. It's character. Anything that is structural I replaced or repaired.
I'm getting the push to light the grill, so later.