Wow the last time I saw push rods like that it was a hydraulic'd HEMI that a guy thought was a submarine. Could it have hydaulic'd somehow? Coolant in cylinder??
when i was a kid my parents had a 1981 ford econoline van that had a 460 in it. it started to bend push rods. my dad ended up replacing the cam and all the lifters. it had at least 2 or 3 sticking lifters.
No P/R guide plates on those.The rockers have a rail on em that straddles the valve stem tip.Thats how they are guided.Its possible the block was decked/heads were milled.This could make the push rods too long.(I doubt this is your problem)I still think your pushrods are too long or the lifters are shot.You cant overadjust those rockers to the point of bending the push rods that bad (they are positive stop)I dont think the engine has been hydrauliced since You say it runs fine...which I cant understand since it has at least one cyl not getting any valve action.I say get the casting #s' off the block so we can determine which push rods you need since yourse I feel are too long.Good luck.
Sorry guys it could have a soft chevy cam in it !!!!! LOL check actual lifter movement to make sure cam loabs have not gone flat.It will run at idle but, miss when revved up.Replace alot of cams in 80's small block chevy engine that did that same thing. Just my 2 cents worth. Randy