Eventually the car died and wouldn't restart. Finally found a working ECU that matched the 1 in the car. Replaced ECU. Car works fine now. There are a couple members here who might have one. But check everything else first. Also, you have to check the voltage to/from EACH terminal (pin) on the ECU. I don't think there's a relay that feeds it. Also, if the ignition has a fault, the ECU would work only when the ignition switch is fully functional. Ignition switch and circuits are easier to trace and less expensive to fix. If there is low voltage to 1 or more of the pins on the ECU, trace those circuits 1st and make any repairs. If none of the repairs help, or if there are no faults in the circuitry, it's the ECU.
The 560 has a totally different system. Yours is electronic injection. The 560 is not. There is a relay for your ECU. On the '73 t is the second one down on the right side of the relays just below the FP relay. Probably the same on yours. Your ECU is on the firewall, the 560 has a different type below the right side floor under the carpet.