I
think this is the answer to your dilemma, and I use the word "think" because I'm used to seeing a
solid brown wire in there, not two brown/white striped. However, take a look at the picture, below (thanks E Sully)
Your shorter wire would connect to a ring connector and be screwed to the housing like the wire with the black insulated connector in the photo, above. Your longer wire will connect to the horn ring or the contact that touches the horn ring.
The above is from an earlier style, hockey puck wheel so some components are different from the bow tie wheel on your 73 but the principle is the same. I'm sure someone who has done this will make any corrections to this post.