I see UNF stud connectors are available on ebay (although round not hex) so these could be the way to go for anyone with the same problem in the future.
However looking at Trigolfs photo Im not sure of the adjustment as the cable stretches. I think I would have shorter joiner and longer threaded rod into the fork so that way the adjustment could be done as always - slacken fork external nut, remove fork cotter pin, rotate fork and its internal square nut to take up the slack and reassemble. That way the joiner doesnt have to undone at all...