I'm in a simalar boat, steerer's are the bain of retrobikers it would seem. My own tale is I bought some great manitou ones. threaded steerer, too short. bought a ti one from ebay germany, the longest they do, cutting the thread off left me just shy of what I need and now I'm waiting for roberts frame builders to come back to work tomorrow and see if they can do me a longer one. thankfully the 1st generation manitous have a steerer held in by big allen bolts so relatively easier to swap than the later forks that are press fitted. If I dont feel its a strong enough join then I may ask them to weld it onto the crown if thats possible.
Its gonna leave me with 2 inch eight steerers to sell. will do that once I have a fix.
One thing to note is the guy in germany offered to cut me a custom length. in hindsight even though it was like 80 euros it might have been cheaper and a better solution than I have at the moment. Grrrr. you live and learn right?