Yes it was oil level. The extra quart resolved the issue. I do think there is excessive leakage internally at the lifter bores. I never saw any aeration in the oil, but maybe you can't see it. My idle pressure hot is low at 20, but solid 35 to 40 at 2K. Continuing to rise to 60 at 4K. Did talk to the engine builder and he has used just 5qts for break in on 440/hemi using the 70 style pan. Those motors have always had high oil pressure, so better internal flow I guess. It is interesting how the windage tray is designed. Oil can only flow out the front and back, until it gets to a much higher level then out the side vents.
Never heard any lifter noise so they must have stayed pressurized with oil. I guess the drop in level really effected the pump head enough to loose flow volume at that higher rpm.