Getting headlight load off the OEM harness does a good job to lessen the issue. I know a guy that makes a nice relay harness specifically for mopars...

The other issue, no matter what 70 oem output factory replacement alternator you use, the idle charge being insufficient to power the car is almost always present. Turn on lights, run the heater blower motor and it's really drawing off the battery, which it shouldn't but does, to keep up with loads. That's why the lights brighten up when you get rolling and RPM is up.