If i understand you right you are losing about 5 lbs of
oil pressure at 5000 rpms. Does it back up more with more rpms. what you see a lot of the time is pumping the
oil pan down before the
oil can return down there. Like mentioned earlier it not that uncommon to see this with a stock style oil pump with the lines, filter, oil cooler and all. we run a lot of engine with a bigger bearing at .003 clearance on the mains and it is not that big of a deal. If you are losing only 5 psi I am not sure I would worry about it very much if it does not go any lower.
Keith