@slikjay, welcome here!
I'm not so much into 50ties but I think this might be battery/cable related.
How old is your battery?
Battery pretty small?
Connectors corroded?
Cable from battery minus to the frame corroded?
All fuses in good shape?
Pls do a junpstart from any donor vehicle (car motor not running) and check your battery voltage with a multimeter when the motor is running. Should be at idle 12+V and revving more than 14 Volts.
If there arrive more than 13 -14 volts, we might look onto your relay.
But step by step.