Are bent pushrods common?

I've got a 65 200 with adjustable rockers. Nearly everything is stock, with the exception of Pertronix. Yesterday, I had a water pump go from a slow drip to a sieve, and the car got a little hot on the way home. Not so hot the temp maxed out or the engine cut out, but still hot. Now, the idle is rough, acceleration is slow, like I am missing a cylinder. Engine smooths out at higher RPMs. I replaced the water pump, checked and replaced the plugs with a spare set, and am going to try replacing the wires with a spare set. Cap and rotor are pretty new and still look ok.

how likely is it I bent a pushrod or stuck a lifter from overheating? I suppose I could have also burnt/stuck a valve, but in times past when that has happened, I got tons of backfiring and blowby out the pcv hole.

Maybe blown head gasket from overheating?

Could be a blown head gasket. But I see no oil in the water, no water in the oil, no water in the cylinders...

Also, heard an intermittent rattling coming from the top of the engine at idle. I thought it may have been the oil filler cap or the air cleaner, but both of those seemed tight. Now I am thinking it is something under the valve cover.

Never replaced a pushrod. Those are about the only parts on the engine still original to the car. That and the thermostat outlet cover.

I think tomorrow I will take the valve cover off and have a look.

bent push rods are kind of rare unless you have something mechanical wrong. i agree with the popped head gasket though, they dont always invade the cooling system either, been there done that plenty of times. its possible that you caught it early.

I took the valve cover off this morning. Nothing seemed amiss. All springs and pushrods seemed straight and tight. All the rubber umbrella seals were in place and not burned. I changed the plug wires to a spare set, took off the pertronix magnetic rotor and looked at it. It looked fine. Car runs about the same. It's drivable for my short trip to work, just runs rough at low RPMs. It did seem a little better after my short drive.

What to check next? I don't have a compression tester, but probably needs to be the next tool I buy. Could the pertronix have gone bad? I thought when they went bad, they completely quit working. I have a spare coil - perhaps I will swap that out. Distributor cap and rotor look good, but maybe a test with an ohm meter to see if there is some resistance I can't see. I know a compression test would be the next logical step, but I probably can't get to that for the next few days. Replace pertronix with points? Perhaps a faulty lifter and try some Marvel Mystery Oil? Any chance this is a fuel system problem? Not much chance of a vacuum leak on this car.

What do you have your initial timing set to? Manual says at least 12* but you'll be much happier at 16 or so. I have mine set to 16 and am happy.

I set timing until it starts knocking, then back off a tad until it quits. I can't trust the timing mark on the balancer any more.