Well the vintage downhill group is great for sourcing parts and advice. If you need a good and cheap machinist, I know a guy I have used for both car and bike parts (he is currently making me a front hub!) - send me a PM and I would be happy to send his details on (he's a one-man-band in a little workshop type, top bloke and he loves doing little weird jobs for people).
What frame do you need the edco for? You could try Jamie Lynn at Mountain Mania.....he's one of the UK's biggest UK retro collectors and owns a ton of old and super rare parts, he might be able to assist (although he is usually super busy as he runs 5 bike shops)...