I would look for the oil supply too, I've seen one head that had carburized oil in the towers to provide zero to the cam. Had to clean passages out with a drill bit, the oil was solid as epoxy. Overheat can do that.
Like they say, best oil pumping tool is an old distributor with gear teeth gone/ground off. We cut the top off and just left shaft sticking out to hook drill up to. Just lower part that goes in the hole and enough shaft to get the job done, you can cut off the bigger part at top and more room to work then.