Sorry, been away for a while, by the text of your story I'm assuming that this is not a new build but just a cam change etc. If it was a new build then I would ask you how tight your clearances were...but that's not the case. I did ask you about the oil pump but got no answer. Are you sure it's not a high pressure or high volume/high pressure pump.
Not likely but there could have been a mix up at the mfg. When I first fired my 331" sbc with a Melling M-55 standard pump and 30 wt. Rotella I got 80 psi with cold oil @ 2500 rp. After the cam was broken in it would come down to about 30 psi at 800 rpm. Did the pump box contain a light purple spring that you could change out for increased oil press? Who knows, maybe that spring is in the pump instead.....by the way what's your psi at 2500?