383 stroker- broken push rods.

I have a built 383 stroker. It was professionally built 10 years ago. It has sportsmen iron head, solid lifter, 501 lift, 9 to 1 comp.
It has 30k miles on it. it was installed and ran great with 100 shot of NOS for 3 years. it was removed due to crash and has been on a stand for the past 6 years. It is now installed in a 66 Nova.
I started it and it seemed to be running good but needed the carb adjusted. I had a local shop look at it. The tech stared it and started reving it up. I don't think it had time to build oil pressure before it was revved up. I got a call from the shop the next day telling me it had a broken push rod. The car has not been driven as it is not done yet. Today I took the other valve cover off and discovered another broken push rod opposite the for first one.
Both are bent and broke clean. They are hardened. I bought a new set but don't want to put them in and have the same thing happen.
Anyone have any experience with something like this. It took me forever to get it up and running so I really don't want to tear it apart if I don't have to.

After sitting for the 6 years, did you prime the oil system before startup?

Before turning the engine over I changed the oil and primed the system. I had it running a dozen times and it held an idle prior to bringing it to the shop. It sounded ok but it took a while to hold a idle. I changed the intake and put a custom 950cfm on top so I knew it needed to be fine tuned. When I changed the intake the push rods looked fine. I changed these parts and oil prior to turning it over after it had been sitting.

All that time sitting, were the valve adjusters backed off while it was in storage??? Was it turned over occasionally while it was hanging on the stand? Could have had a few valves hanging open because of crud building up in the guides while it was sitting.... Were the valves readjusted prior to firing it up????

I did neither. The oil seemed to be flowing good. It never occurred to me to adjust the valves. How can I check to see if that was the cause?

Sounds like the lash wasn't set correctly, & // or the guy took the RPMs way too high without being under load ( driving or dyno run ). RPMs climb fast without being under load.
** Of course I may be way off on my opinion.**
Personally I don't rev above 25-2800 in park or neutral. That's plenty for checking for vacuum leaks, throttle response, checking for fluid leaks, fuel pressure, fuel flow from a carb, listening for odd noises.
Spring pressure, valve float, piston contact come to mind.
Any kind of knock or tap prior to the event?

There was no tapping or odd noise prior to bringing it to the shop.

Who had it??. K-S??.

yep seen it who.s rocker arms the older pro comp s? the push rod cups were to deep in the rockers shear in to the pushrod s in time fail if not right off ...fix was 210 pushrod tips . rocker geometry could be off as well . as old worn out valve springs and someone sent it in to valve float some of the valves frozen up on valve guilds or bent valves stems will hang up. like other.s have said

If it where mine,I think I would want to tear it down for inspection of other possible damages.Maybe leak it down before hand and freshen up the top haft.

Iv got a new complete set of Manley 4130 swedged end 5/16 x 7.800 pushrods.
I'm torn if I put them in and make sure the oil is flowing and everything seems tight before putting the covers back on or tearing it down.

It's prudent to pull the heads and see what you find. All it costs is a set of head, intake and maybe carburetor base gaskets, and a little time. Pushrods don't bend without something binding up, and you didn't just bend them, they bent to the break point!