Inconsistent starting in 85 c 10

[b1v3r]

1985 Chevrolet CK pickup

Replaced Items:

Ignition switch on steering column above brake pedal
Ignition module (twice)
Spark plugs and wires
Fuel pump and filters (filters twice)
Battery and alternator
New gas (added SEAFOAM to get any residue water out)

Starter turns fine
Gets plenty of gas
Battery is fully charged.

Scenario:

Starts inconsistently. Rain or shine, day or night, first time or after several starts. If it starts, it runs like a new truck. When it doesn’t start, you can use gas in carb, starting fluid, etc but it will not start. When it doesn’t start, there is no spark, but does get gas.
Have distributor from another running truck, but am unable to install it. I was told the cam sensor was inside the distributor. I was also told there was a crank sensor, but I was also told there wasn’t one on this truck.

Would like to get truck fixed as I can’t afford car payments, at this time, and I need dependable transportation for both daily driving and trips to SA and back. If possible, would like someone to repair it and allow me to make payments, if necessary.

Any assistance would be greatly appreciated.