[andyh1956]

At this point you have to determine if the problem is electrical, mechanical, fuel or a combination. Since the problem manifested itself all at one I doubt it's a combo.
When you try to start it does the engine spin at it's normal speed or does it drag?
When it tries to start does it try to kick back?
When it won't start look into the carb while you pump the throttle lever & see if it squirts fuel from the accelerator pump.

Next I would rotate the engine up on #1 cyl Compression & the pull the distributor cap off & look to see if the rotor button is indexed to the #1 plug wire.
That's where I would start.
Your truck has an early HEI distributor & the rotor button has a built in resistor that is a well known failure part. A very inexpensive part to try & you need a spare in the glove box anyway.