I have rebuilt a few 235/261 engines and never noticed any difference in the head bolts other than the bolt length.The oil passage is detoured away from the bolt near the top so it feeds into the passage the rocker oiling tube.Remove the head bolt next to the rocker oil feed and push a length of stiff wire in the hole till it bottoms out. Note if there is sludge on the wire .replace the bolt.Remove the distributer, after noting the rotor position. using a drill motor with an old screw driver shaft or something similar, rotate the pump clockwise. Oil should flow out of the rocker pipe feed hole after a minute of so. If not try spraying some carb cleaner down the hole to clean it.
