[massey478]

I would say it is more the result of stuck valves, that is usually the cause I see. I cannot remember if these engines are interference motors; that is, if the pistons can hit the valves if they are stuck open. I think they can, just cannot remember. Yes, if the piston can hit the valves, then if a lifter was stuck in the up position or a valve in the open position because it stuck in the guide, the piston would force the valve back toward closed, and if stuck lifter or valve guide resistance is enough it could bend a push rod. My experiences tend to make me doubt the stuck lifter though but Murphy is an expert at making unexpected things happen! Your lifters are not stuck as you describe so they are not the problem if they ever were. Now, if the pistons hit the valves, a valve head could be bent. Take a hammer and tap squarely on the valve tips hard enough to move them and see if the ones in question snap open and shut with the hammer blows as they should. If they do not do this then they are sticking in the guides. If repeated hammer blows do not loosen them then also try to get some aid like Liquid Wrench applied through the spring at the top of the guide then continue hammer blows until loose. After all is well replace the rocker train, set lash, and then is is best to run a compression test to see if a bent valve is dropping compression in those cylinders. We get a good idea of even compression across all cylinders quickly by just grounding the coil wire and cranking the motor with spark plugs in and the throttle wide open. If you hear a speed-up of the starter motor on certain cylinders as it cranks then suspect low compression in them and go ahead with an actual compression test.
Actually an engine that has had recent repair work done to it like new valve guides, new pistons and rings and such is worse off in long storage if it has little time on it because clearances are still tight and a coating of oil residue has not yet built up to protect parts. When we get a motor we take the valve covers off and check it. When we see the old greasy coating from oils on the parts we know we are probably OK it has been preserved. If it is very clean, then careful checking is needed to be sure it has not had rust form somewhere like the valve guides, cylinder walls, etc. We have found that motors that have had synthetic oil run in them do not survive as well in long storage. Synthetics do not build up the protective coatings mineral oils do.