Stubborn starting question...

Bear with me. I'm new to this list, but not new to driveability.

Nobody has mentioned the possibility that his timing chain may have skipped a tooth, am I right?

To run well, you need fuel, a good and properly timed spark, and good compression. If you didn't have to move the distributor very far to re-establish good initial timing, your timing chain is probably ok. But if you had to move it quite a bit... check your compression. If it's low, odds are your timing chain has skipped. After all, your car ran well, and then was a "little" rough at idle (where the chain slops around) and did NOT start after shutoff, in the convenience store parking lot -- a classic symptom of timing chain problems. If this is the case, you can install all the electronic ignitions and new carbs you want without fixing the problem.

Another good way to investigate a loose chain is to put a socket on the crank (I'm assuming you CAN on the 273, I don't know, but if you can't, then use a strap wrench or whatever turning device you can "McGyver") and then take the cap off of the distributor. Work the crank one way and then the other. If you get 10 degrees or more of movement on the crank before the distributor rotor moves then, Houston, you've got a problem.

1. Good spark, properly timed.
2. Fuel.
3. Compression.

These are what you need.

Hope this helps.

Ex-tuneup mechanic,
JD