Maybe this will help. The tubing may be tricky, especially without the stock pieces to compare. I had my entire dash out a few months back, so naturally I had the tubing out, too. As you probably know, the tubing links into the slots in the wheel boxes. As I recall, the flaring looked fairly simple and could be done with a standard flaring tool, and the tubing appeared to be like simple fuel line.
Someone may correct me, but the tubing seems to do nothing other than hold grease and guide the drive cable. I think that with the wheel boxes in hand, and the measured distance between the two, you could make the tubing with a flaring tool and be just fine.
As for the nut, I'd think that a good shop that carries specialty auto fasteners (like Scott Supply in Tucson, or Arizona Bolt and Nut) might carry it. Moss calls for a ferrel, but I think the tubing was flared at that end, too--it's definitely flared at the wheel boxes because that's how the tubing is held into place.
Hope this helps. If I were you, I wouldn't be afraid to make them on your own. It could be a fun assignment if that nut is available. I suppose the threading could be an issue if it's whitworth. Best of luck.