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.