Only one thing bends push rods or pulls rocker studs---interference. Could be several things but spring coil bind or valve to piston are the most common. First turn engine to point of maximum valve lift and see if a thin feeler gauge will slide between spring coils. To see how much clearance you have put a piece of solder between coils when valve is closed and make two revolutions of the engine, remove solder and measure how thick it is where crushed. We have a home made tool to work the rocker to check valve to piston clearance but I think they make them for sale. With a magnetic mount dial indicator you can find the point of the least valve to piston clearance then assemble with push rod and see if rocker gets moved beyond the known interference point. None of this should be necessary if the engine builder didn't have his head buried in a dark odorous place. I am not a teacher and Jerry was for a number of years so his explanation would have been much better so make note of lesson learned.
