Ok, this will bring things pretty much up to date. A picture of the seat I want to use, this type because it's going to be in the vein of a late 1920s to 1940s style but not based on any one brand.
And some pictures of the steering levers. I'm using hydraulic brakes on the CC rotors for steering. I found out the calipers and master cylinder from what they call a "pit bike" would work and are not much money.
seat.jpg
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20220604_154928.jpg