Left to Guess .. It's for 9/8" threadless forks?, when you get it, let the list know..
Sean may be best served by getting a fork Made, by a frame builder.
In addition to UK imports, contact Bruce Gordon, In Petaluma California.
Touring frames and forks is what he does a lot.
Perhaps one of his BLT forks will be suitable, BG designed TW import.
they are made to fit Bruce's excellent low rider racks
[my racks have gone thru 2 frame changes, in 25 years, still fine]
1" threaded, quill stem on the BG bikes so that may suit your needs..
http://www.bgcycles.com/