Hi. I have a couple of forks that may fit the bill depending on the length of your headtube.
The red pair of forks are actually for use on an Orbit touring tandem, but were never fitted. The steerer is threaded 1 1/8" - length 170mm of which 50mm is threaded. Underside of crown down to axle is 355mm.
The Kona Project 2 forks have an unthreaded steerer - length 207mm. Underside of crown down to axle is 362mm.
Either fork £30 + £5 postage. If they're not what you need, good luck in your search.
Mark. 07948 164188.