check the switch module down on the steering post ,This is where the switch working is .
the switch by the steering wheel is just got a rod that runs down the the module on top of the stiring shaft check the wires also at the module
Another option is put in a HEI distributor.
DONT GIVE UP.
MY 1980 FORD HAS A DELECRON ALTNATOR
ALSO CHECK THAT YOU HAVE A GOOD GROUND FROM THE BATTERY TO THE MOTOR.
Check both ends of the battery cables .