At this point I want to ask "when did you notice a problem?"
If the problem was noticed because the tech was watching to confirm that the rocker train was oiling after starting engine before releasing unit to service (valve cover still off), it is possible that no damage has been done to the rocker shaft and rocker arms.
But, if the problem was noted only after the rocker train became noisy................you are going to have to replace the rocker shaft and all the rocker arms! There will be heavy scoring to both the shaft and the rocker arms.
We had a truck sent to us from another terminal because the engine was making rattling and squealing sounds after a vendor to that facility had replaced the head gasket.
The noises were the result of damage to the rocker shaft and arms from no oil.
Yep, head gasket upside down.
Questioning the folks at the other terminal revealed that the noises began about 3 days after the head gasket was replaced and unit returned to service.
Had to replace the rocker shaft and all rockers.