You have an electrical problem. You recently did electrical work in the form of replacing your starter motor. Did you disturb any wiring other than the wiring at the starter?
did you by chance do anything with the connections on the starter solenoid, mounted on the firewall behind the passenger seat? That solenoid is the power source for the ignition coil
Did the car run after the new alternator and voltage regulator were installed?
The power to the “A” terminal on the voltage regulator is sourced from the battery terminal on the alternator. FYI, brand new voltage regulators have been known to be non-op straight out of the box
Larry