Ideas on what's causing my click/tick/rattle noise?

my68barracuda said

Along with everything you mentioned, I would put a mechanical oil pressure gauge on that motor.
That engine has every indication of too much oil up top and too little to the rods. It will show as low oil pressure with the engine rpm’s up.

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Drainback issue somehow? (or lack thereof) Had that on another of my parents' cars (was a GM product with a sludged up Olds 350, Dad had bought a previously poorly maintained car) Not saying your fresh motor would be sludged, maybe some casting flash blocking the drainback path? or something goofy with the head gasket? Just a thought. On that Olds the drainback holes were completely plugged, I never got such a flood of oil over the head just by pulling the valve cover out of any other vehicle that I have had to work, on as I did on that one.

Though I understand where you are heading with what you are saying, about being flooded with oil. Hi volume oil pump, being used? that would aggravate the issue too.