You will have to disassemble and blueprint any pump you buy, so check out the one you are running so you can eliminate or confirm it as a possible cause of the problem. At only 10 psi your valve spring pressure is collapsing the lifters. You should have enough oil pressure at idle that it sprays the underside of the hood, not just barely trickle out of the pushrods. You absolutely will loose oil pressure through the bearings if the bearing clearance is too much. You will loose pressure even if you have too much clearance on a cam journal or if the lifters have too much clearance in the lifter bores.
