Not sure on the thread size but google can give you that. You don't need the threaded bar, just a nut welded onto a long bolt, or anything like a bar/massive nail with a socket on it would do.
I know its not ideal but the chances of finding someone close enough are zip. Or you could try and find an injector refurbisher, if you convince them you will bring the injectors in to them they will loan you the slide hammer.