Well that's not quite right, either. Any mechanic has seen numerous 60s/ 70's cars which had worn out "slipped" nylon timing sprockets drive (poorly) into the shop, coughing and gagging.
An engine WILL run under certain conditions with the cam or ignition out of time, and while running poorly, you won't be able to pin it down to "just one" or two cylinders
If this were me, I'd do this............
Carefully rotate the engine, watching for proper valve opening / closing on each cylinder
MAKE CERTAIN ignition is OK. You can swap plugs and wires from one cylinder to another and see if the problem moves.
Do NOT "pull" plug wires. Instead, SHORT them to ground with a clip lead and screwdriver, or other grounded probe. On older cars with conventional distributors, I usually do one of two things..........
Either pull up the dist. boots and insert small brads / nails down beside each wire, so you can go 'round and ground one at a time.
or........
Pull one wire out one at a time and at the same time, slide your ground probe into the dist. cap
Listen as each cylinder is dropped, use a tach or vacuum gauge. Each cylinder should drop the same
Once you ID the one, the two, or whatever "bad" ones, MOVE those plugs, or replace them and retest.
Then move the plug wires to other cylinders and retest.
If the two cylinders are adjacent, suspect a leak between cylinders. This should show up with a pressure test, but may not
Buy or make yourself a leakdown tester. Google it.....they are easy to make.
Inject air into each cylinder at TDC and listen for leaks........at the carb, at the tail pipes, and in the radiator cap, and look for bubbles in the coolant.