help me find an electrical gremlin, please

I agree that a multimeter is a great way to check things like this out - if you have voltage at the coil, then there is another problem. My past experience with engines cutting out during a ride always had to do with either points (not your case) or with the ammeter. If it's the ammeter, all of the fused circuits will be dead. If not that, then check the dist., the ECU, the starter solenoid and the ballast resistor (plus the coil if it hadn't already been changed).

Wish you were closer, I love figuring out these problems!

Best of luck!