[John Rogers]

You might want to try aviation electronics supply stores as that is what I bought when I modified my vintage race car. I disassembled the steering column and pulled the wiper switch and the turn signal arm and added an on/off switch for wipers in the dash with a sealed six wire connector I bought at a surplus store in San Diego. I looked and Aitcraft Spruce & Specialty Co is still around and they have electrical parts.

A couple handy hints, first when working under the dash, pull the driver seat out, use several pillows and lay on your back with a nice LED shop light so it is easy to work on. Aalso note there was a groove in both our 914s, a 73 and a 74 that allowed a thin bladed screw driver to be inserted and pop the connector(s) apart. On some cars that groove might be covered over with vinyl from the dash.
John