1984 Other Chevrolet Models intermittent starting

Sounds like the starting system is fine. You have compression if the engine runs fine when it starts. That leaves fuel and spark. Check for fuel at the engine the next time it wount start. If your not getting fuel then the pump has stopped pumping for some reason. A bad pump, a bad ground on the pump are all likely. Also a bad crank sensor can cut power to the fuel pump intermittently. This will also stop spark so pull a plug and crank it, if you also don't have spark suspect the crank sensor, computer, or someother sensor to the ECM. Good Luck