Hi,

To find the number one you align the crankshaft pulley TDC mark up to a line going vertically LINE that is located just to the right of the protrusion that holds degree marks for more BTDC.
It is a raised surface line just as black as the rest of the cover.
Many times it is overlooked as a timing light will never light up on that line but on the 12 degree spacing between 10-15.

The cam lobes will be sticking upwards but each to either side away from the other like a dogs ears when a dog cowards. You see that by looking in through the oil cap hole.

You will have to take the single screw out that hold the two top pieces together. The cover will flex back some but I find that taking the two lower bolts out gives in to more flexibility.
That intermediate sprockets, that drives the distributor, has a dot that cannot be seen.
You’ll have to check the under the distributor cap to check if it is directly underneath the number one terminal.
You may want to check the rotor button for any cracks in the top as there is a resistor under the epoxy with the brass terminal for good measure. You say you have spark but unless you lay all the plugs out to ground to completely verify.
You might have a loss in between.
Spark plug wires can fail but all four leads back to the above or the coil wire itself.

The rotor button can just quit. I have had two go bad across my six cars in about 50 years. So rare, yes, but I carry a spare anyways.

With all of these possibilities, the starting fluid is a big help to verify ignition spark or lack of fuel delivery to the cylinders.

Yes the FPR becomes a possibility as it is only a spring loaded rubber diaphragm with a check ball on the other side. They are designed to drop the pressure down to a preset and also leak fuel towards the intake upon cranking. Poor starting is a first symptom. Hot or cold.
Some people pinch the return line to artificially raise the pressure when they have a gauge or not.
It’s a quick and dirty troubleshooting techniques. But sometimes you do what you can to see what happens before whipping out a wallet.

That’s one of the beauties of these cars.
You don’t need a bunch of sophisticated tools to repair them. I have used a plastic bag to troubleshoot with.
It’s a matter of learning something about the sequence of what it’s takes to get its act together.
It’s physics of the first order involving the combustion triangle on ALL cars.
YOU NAMED THEM!

I’m sure there is some explanation “lurking around” to be found.

Good luck to you this weekend.

Phil