Is it correct to think that it will crank over with the starter but not fire? Is this the original distributor with points? Did this just happen overnight? Do you have a voltmeter?

Does it want to catch while cranking but just dies when you release the key to RUN? If so, the ballast resistor is bad.

For a more orderly procedure for the original points distributor system:

1st, clean under the dsitrbutor cap with a dry cloth and check the rotor button. Check the points gap when open and re-try.

2nd, temporarily disconnect the condensor from the points in the distributor, If it starts, then the condensor is shorted.

3rd, take the spark wire from the coil off of the distributor and place it so the open end is about 1/4" from the valve cover; crank and see if you get a good spark to the cover. If so, then the issue is likely in the rotor button or distributor cap.

4th if no spark above, then you can test the coil by:
- Disconnect the wire from coil-.
- Connect a wire jumper to ground near the coil and turn the key to RUN.
- Touch the ground jumper to the coil - for a moment and then disconnect while watching the spark gap in 3 above. You should get a good spark each time you disconnect the ground jumper from coil -. BE CAREFUL to not be touching the wire when you do this as you can get a good jolt from the coil-.

5th Get a voltmeter and make sure you are getting battery voltage to the ballast in RUN, and also check to see that you are getting battery voltage to the coil+ when the key is in START and the engine is cranking.

6th If no spark in 4 above and you have the voltages described in 5, then replace the ballast resistor (cheap) and re-try. If nothing, then replace the coil.