The '70 wiring diagram shows connections for either a Holley or a Carter for the 383. It appears there is one black wire for the Carter, and possibly a different, alternate wire for the Holley. It's not possible to tell from the diagram what this would physically look like. One test would be with the ignition off to check for continuity between the two connectors. If there is continuity, my best guess would be that they were both carb wires, don't know exactly what for. I'm not familiar with '70 383s, but on my '69 440/350 it had a mechanical choke. If this is what they are, it appears they would originate on a connector for some sort of solenoid on the distributor. The fact that you're getting voltage to them with the ignition on leads me to believe this solenoid might still be hooked up?