[Sirrotica]

Both valves will be closed is correct. Remove #1 plug wad up a ball of paper and sit it on the plug hole. As you turn the engine over by hand it will blow the paper off of the plug hole, you're on the compression stroke. While you're removng plugs you might want to look at all of them to see if there's one that looks particulary bad, narrows down your search to 1 cylinder.

Did you idle the engine with the valve covers removed? That's the best way to see if you have a lazy cam lobe, you're not going to see anything by just examining the rocker system with the engine shut off, unless the rocker arm has fallen off completely.

You're also going to be looking for push rods not slowly spinning. When they aren't spinning the cam, and lifter is going flat, also for sluggish movement as they aren't moving all the way to open the valve as the cam no longer has full lobes left on it.

Rebuilding a Rochester 2 bbl is pretty simple, follow the directions in the kit, or a manual detailing how to disassemble it and re assemble it, setting the adustments, and getting sediment is paramont, then adjusting the idle mixture screws to get the smoothest idle.

Pulling plug wires one at a time at idle will narrow down which cylinder is missing, then you have narrowed your search to usually 1 cylinder.

Hope maybe something helps you narrow it down.