Thanks for all the answers everyone. I found an old 9x12 folder camera (that I guess technically was my first "LF" camera) and took the lens from it, it's even got a shutter. The original lens was a 135mm, but after unscrewing the rear element it seemed to become something significantly longer (probably around the 200m) mark. I haven't been able to test it properly since I lack a lens board of the correct size, but I was able to sort of keep it in place on a larger lens board and observe the image on the ground glass.