Casey, here is a website address that you might try.
[
www.ajreeves.com]
Look at the 3 1/2 inch gauge stuff and Tich is found there.
The site is in Great Britain and the prices are in Pounds Sterling. I also have a " Tich " in the same gauge, needs a pair of clack valves to get it up and running. The engine has had a pressure test to 1 1/2 times operating pressure, but the valves leak down slowly and won't hold the pressure. Good luck on the build .
Charles