I have just redone 1658, replacing all hardware. The Harken catalog was invaluable. It used to have an Ensign specific set of pages.
I have a couple of jib sheet cars and blocks that you can have for a song. Not sure about about the size of the track, which, BTW is not called a traveler. A traveler is a control line car. The track is called simply the jib sheet track. The pieces you are looking for are called a spring loaded standing block and jib sheet car.
Good luck. Let me know if you want my old set, which is in good mechanical condition.
Stan Murphy
Nana 1658