The cable and casing have unique part numbers, meaning they are not parts borrowed from another Kaiser. I recall breaking the cable on my car and found a suitable replacement at NAPA. They sell a universal cable that can be cut to length. The correct square end can then be attached. Of course, a cable won't be of much help if you need the casing as well.
Unfortunately, I don't have measurements as I no longer own my Darrin (much to my chagrin). Perhaps someone else with one could measure theirs...it might be possible to adapt another to work.