340 help!

After the cap is all dried out nice, and the issue persists;
Push the car out into the yard.Pull all the plugs out. Disable the spark by disconnecting the power to the ECU/coil. Clamp the rubber fuel line somewhere between the carb and the pump. Bring a fire extinguisher to somewhere near the car where you can see it but no closer that a car-length away, and off to the side.
Then,crank the gas out of it. A short burst of 1 second, then another and another. Until the gas is stops pouring out. Take the extinguisher and walk away, far away. Twenty minutes later come back and crank it for 15 or 20 seconds. Go clean your plugs. If gas did come squirting out of the plug holes, you have a carb issue; take it off and fix it. If no carb issue, squirt a bit of oil in each hole. Then crank it a few revolutions to distribute the oil and blow out the excess.
Now we have only two or three options, either there is something wrong with the valves, or the gas is not 100% gas, or the valve/ignition timing has changed.
The easiest thing to do is to test for compression, I mean the plugs are already out,right. If the numbers are normal in every hole, we can rule out a jumped chain and stuck or bent valves.
The next easiest is to put the #1 piston at TDC compression, then back it up 15 degrees, Pop the cap and make sure the rotor is under the #1 tower. This too proves the chain is where it was the last time it ran, and it proves the timing is close enough to at least start and run.
Thirdly is to prove the gas is 100% gas,fresh enough to burn.To do this you will need to drain and capture the fuel from the very bottom of the bowl. On a Holley this is easy. But we especially need the very first couple of teaspoons.Drain the entire bowl into a clean transparent container. Check it for water then color. Red is bad,useless.Orange is stale,will work in your lawnmower,maybe. Light yellow will burn. Fresh gas is clear as water. There should be about 50ccs of it. So if you got clear to light yellow and no water,pour it back in, thru the bowl-vent.If the quantity was close to 50 cc,release the clamp.
Put the cap back on,reconnect the ECU/coil,put the plugs back in, and try again.
My guess is the cylinders were just dry, and the rings were not sealing and so the pistons were not pulling hard enough on the fuel circuits.But you cured that when the oil went in the plug holes. It should bark to life now.