The
oil hole in the rocker shaft should be on the bottom since the valve and pushrod are pushing up on the rocker and the lubrication needs to be at this point. Your photo shows the hole on the top. Basically you were running without
oil and the rocker walked off the valve.
One other note: the rocker hold down bolts you have are not the original Ford products. The oiling bolt is special and you might also have a restriction there.
Dave