This is probably very close. You are not getting oil to the top because of the wrong lifters or pushrods or ?????? It clicks and pops when you shut it off because things are getting hot and seized and "snapping" back into place after running. I would bet money that some of the valve guides or valve stems are screwed at this point. Don't run it any longer. Pull a valve cover and inspect for oil--I bet you don't have any up top. J.Rob