Hi Jason,
Wow, these are some great pictures of seldom-seen early hardware. Thank you for sharing this project with us.
I wonder, how much truly early narrow gauge rolling stock is still out there? I'm sure it's not much at all, especially if we're limiting ourselves to cars from the 1870s or even the 1880s.
For example, I believe the earliest surviving car from the Maine Two-Footers is SR&RL Tool Car 562, a 24-foot boxcar built in 1883 by William Dyer for the Sandy River RR (original number unknown), but I have no idea if it still has its original draft gear. Thera are five surviving Maine Two-Foot passenger cars from the 1880s (SR&RL combine 11 and coaches 17 and 18, and B&SR coaches 15 and 18, all built by Laconia), plus one SR&RL crank handcar from the 1880s, but that's it. Everything else is from the 1890s or later.
-Philip Marshall