74 Dart won't start - ignition switch - maybe starter relay?

I'm hoping you electrical gurus can help diagnose my problem. I just got the motor back in my dart and it ran awesome for about an hour! I started it at least 5 times, but now I turn the key and get nothing.

I've done a ton of reading on the forum and did a few tests.

• I tried grounding the neutral safety switch with no luck. I get 0 volts at the starter relay, so the NSS checks out.
• On the starter relay, with the key in the start position I get 12.5V at the top terminal from the battery. 0V on the square terminal going to the starter solenoid. 0V on the terminal from the ignition switch. 0V on the terminal from the NSS.
• I have 12.5V at the bulkhead connector after the fusible link
• With the key in the run position I can get the motor to turn over if I jump the solenoid at the relay, but it will not run.

Any advice on what to try next would be much appreciated!