Maybe restating the obvious, but on most 60's mopars the green wire was the power to the rotor. I assume the early cars like your Lancer are that way too.
Whoever converted the car to use the '70 up regulator and alternator could have used whatever colors they wanted, in whatever way they wanted, and easy enough to mix 'em up too. That's why I suspect that, or some insulation has rubbed off.
Take the connectors off the regulator and alternator fields. Check for continuity from the ignition run (ballast resistor is usually an easy place to access) to make sure the positions on the connectors are correct.
Insulation rubbing off is another issue sometimes. Wires get pinched or move around and chafe. I've come around to following the factory routing as much as possible and taping or zip tying the additional wire to the existing harness.