won't start....

I pulled my slant six and swapped it for a 360 magnum. I was very careful not to change anything in the wiring, I marked everything and simply reatttached. I did put a different neutral safety switch in the new tranny. When I turn the key I get intermittent power, i.e. my volt gauge in the dash shows battery power intermittently. But even when it's showing power, the ignition wire to the starter isn't getting power when I turn the key. I tried in park and in neutral. My battery is good, I bench tested the starter, it's good. My headlights, flashers, etc. all work. Is this perhaps a bad ground to the engine? Any ideas? Everything worked perfectly prior to swap.

This is a '67 dart, A904.

Note: I also note that my horn isn't working. I hear the relay click, but no horn. Perhaps unrelated, but just fyi.