66 Dart/74 la 318 starter issue

Are you using a known good starter? I would back it out to make sure it would run unbolted from the engine. Can you turn the engine over by hand to make sure it's not frozen. Just trying to cover the basics that can cause a starting problem
Yeah, it starts perfectly every time if I use a remote start trigger wired directly to the terminals on the starter. And a brand new relay. I have discovered some weird wiring things tonight, and think I’m about to go down a real bad wiring rabbit hole. A wire through the firewall beside the throttle cable is attached to the ignition terminal on the relay, but the wire from the bulkhead that is supposed to go there is just hanging loose, and getting 12V with the key turned to start.