I can't help you specifically with the steering wheel rebuild kits, but you can probably trouble shoot your horn easier than you think.
For the horn system to work, you should have a horn button (you gotta figure that one out), the horn relay, and the horn itself. The relay is typically a 3 prong (if I remember correctly) silver relay. It's mounted by itself over the fenderwell (passenger I think). If you didn't have a horn before, double check that your horn works (hook it up directly to the battery). double check that you have a relay present (can't imagine someone hacked it out, but you never know). you can check to see whether your horn switch works with a multimeter (test for continuity--0 ohms--when you press it). I would just play around with the switch until you get continuity when you press it(maybe you don't need the springs?). A wiring diagram may also help clarify some things--there's probably one on this site. Don't know if that helps at all or even if that's what you're after, hope it's a start though
Edit: browsed your gallery, realized maybe the original harness is gone? Maybe just fab up a new system (maybe that's what you were asking all along?) just mimick the wiring diagram