Usable diagrams at MyMopar
(Be careful, I've found some mistakes in a couple of years, I think the bulkhead connector labeling)
http://www.mymopar.com/downloads/1973/73ValiantA.jpg
http://www.mymopar.com/downloads/1973/73ValiantB.jpg
which came from here:
http://www.mymopar.com/index.php?pid=31
Are you using the original 4 terminal ballast, or 2 terminal ballast?
Some info on the electronic ignition
http://www.mymopar.com/downloads/elecignconv.pdf
older 5 terminal ECU with 4 terminal resistor
http://www.mymopar.com/downloads/Ignition_System_5pin.jpg
Newer 4 terminal ECU with 2 terminal resistor:
http://www.mymopar.com/downloads/Ignition_System_4pin.jpg
YOU MAY HAVE multiple problems
ONE First make sure the battery does not have a "drain" on it from the system. Remove the ground from the battery and connect your test light from the battery NEG post to ground. Do this in a shaded darkened area. ANY light from the test lamp indicates a system drain. Make sure the glove box, trunk light, underhood light, all courtesy lights, etc are off. Make sure the cigarette lighter is pulled out, radio off, etc.
If you show a drain, start by removing fuses one at a time until the drain goes away
NEXT Your system DEFINATELY is not charging. But it SOUNDS as if you may have multiple problems.
IF the battery is in good condition AND is charged up, it should be able to start and run the car several times. You should be able to drive it many miles in daylight, and at least several miles at night with headlights.
SO remove the battery and either substitute another temporarily, or have it load tested. Be sure and charge it first, and let it set at least an hour before load testing.
IF THE ABOVE is OK, next attack the charging system.
Pull the connector off at the regulator. Turn the key to run, engine off. Remove both "push on" connectors at the alternator. Use your test lamp or meter to determine which one is "hot" with key in run, and it should be the BLUE wire.
Reconnect the blue wire. Take a clip lead and GROUND the remaining alternator push-on field terminal.
Start the engine, and gently bring up RPM. The ammeter should start to show a charge, the more RPM, the more charge. Don't "go nuts" as you are running with NO regulator and you don't want the voltage too high.
When you get this far, post back.