I uploaded a video with it running without the valve cover. I sure don't hear the noise. Maybe some under acceleration, but that may be piston slap. It blows out about 1 quart of oil every 15 seconds.
edit: after driving for about 15 miles, the noise is back, but not quite as bad. The only thing I did when I had the valve cover off was to rotate the buckets covering the valve springs. They moved freely. I'm wondering if one has a worn spot.