Short circuit 63 Dodge Dart

“Restored” and “verified” has a large swing of meaning dependent on who you are.
As for the spark- not normal. Try pulling the fuses as suggested. Also, it is possible the voltage regulator is stuck “closed” inside the black box on the driver side of the firewall. You may have a mouse who liked the wires more than you do. Until you find this short- leave the negative terminal disconnected when you’re not around. Fire prevention.