an electrical nightmare , please help , 1972 dart

I put in a used swap meet alternator . It seems to be charging normally right now . At first , it was still overcharging . After twisting the wire connections , below the steering column , during a test , it went to charging normally . I will chase that later . For now , i want to fix chase possible bad ground .

The headlights and front turn signals don't light up . With the headlight switch on , the side marker lights , the fender mounted turn signals , the directional and high beam indicators in the dash , all light up solid . With everything connected , the foot dimmer switch is getting power to all three terminals . About 7 or 8 volts each . The headlight terminals are only getting 0.18 v .

I have cleaned up the grounds on the radiator support , the block to battery cable , and the block to firewall strap . Is there a way to test the grounds or the wires ? Are there any more grounds for the headlights ? Does the starter cable connections have anything to do with that ? One of those looks somewhat corroded at the connection .