I always find it useful to have a dimensional frame of reference in these kinds of shots. I took pics of pretty much everything while it was apart. Here's a few more that some future visitor might find useful.Thanks for the pictures with the tape measure, now I know what my extra set of truss rods are for.....I knew they were Shelby but didn't know the year.
Downtube: I think I was burning an inch at the top of the downtube, which makes the center of crank to top of seatpost look like 20" in this picture. I had a smaller number in my head, for some reason. Parallax?!
The prewar "snowflake" chainwheel was put on the bike by the previous owner.
I don't know how long images attached in this way will last? Some years ago, I diligently setup a cloud storage, and dutifully attached images as links, but that site lost the domain, and all my links were broken. I do size them down a bit before pasting them here, so hopefully I'm not wasting too much data space?
After riding the bike for a few days, I have to say that I'm not unhappy with the 52/20 (26/10 skiptooth) drive ratio.
This sprocket ratio with the 26x2.125, 559 tires gives 67.4 gear inches, or a 5.0 with Sheldon Browns "Gain Ratio" which takes the length of the crank arms into account. https://www.sheldonbrown.com/gear-calc.html
My English 3 speed, with it's 26x1-3/8 tires on 590 wheels and AW hub running 48/18 gives me
Gear Inches Gain Ratio
Low 51.8" 4.0
Mid 69.2" 5.4
Hi 92.1" 7.2
I think either of these systems beats discussing ratios only in terms of sprocket teeth counts, because the sprocket ratio number doesn't account for the considerable effect of wheel diameter and crank length on distance traveled and effort required. Here's more info on the methods. https://www.sheldonbrown.com/gloss_g.html#gearinch
I can push the Hiawatha up to it's cruising speed without too much trouble. On my 5.6 mile commute, I've made an average travel time of about 32 minutes, including stoplights and a mild morning quartering headwind. That's 10.5 mph average, and better than I can manage in the car, which is sorely limited by traffic and traffic control devices.