Here is my theory. When the engine temp went up your oil thinned out to the point of allowing your lifters to partially collapse which allows excessive valve lash.
I would sort out whatever caused your overheating in the first place, change the oil and try it out. If you are still getting noise after that try to figure out which side of the engine you are getting the noise from and pull that valve cover. Run the engine at with the valve cover off and try and figure out which is making your noise using a screwdriver with the tip on the head next to the rocker and the handle against your ear. After listening to to each of the 8 lifters use something like the wooden handle of a hammer to press down on the pushrod side of the noisy rocker (with the engine running at idle) untill you start getting more oil coming out of the top of the pushrode. Hopefully this will help free up the stuck lifter. This is definitely a shade tree method but often it works and will save you from pulling the intake off to replace a lifter. Good luck and try not to make a mess.