Excellent news! Surprised you had a bad earth due to the paint, usually I just get wire blindness and miss an earth
Check the blue altenator exciter wire is on the correct terminal on the altenator, often there are two terminals, often only 1 works.
That big purple/black wire is the terminal 30 feed to the ECU, etc, should be fed by an ecu controlled relay. Im guessing you've got it plugged back in now, fairly sure they dont run without it.