[RICK LAKE]

caprimanic Before you get crazy on this, I have seen this before with windsor motors.
6 things cause this, There is too much clearance between the stud and the rocker. sloppy in the hole. There was no stud gridle to control the rockers and stablize the studs. How many times was the motor banged off the rev limiter? Poor oiling between the trunion and the stud.The wrong pushrod length. You also have the rockers hitting the springs, see the 2 marks on the under side. I think going back through the geometery of your valve train is needed. It looks like not enough clearance. Like to see the other rockers on the under side too. What was the coil bind on this?
From the pictures, I am going with over revving and banging a limiter. Valves banging rockers and cause deflection.
You might also want to recheck the valves, some of the stems have a wierd wear pattern on the shafts. Looks like the chrome is being worn off. Rick L.