I am having a bit of trouble trying to determine the level of your rebuild. Was the crank turned? were the cylinders Bored and honed? were the heads rebuilt? were the cam bearings changed? If not, I would call it a refresh. If a crank is not turned, that could easily be the cause of your low oil pressure.
Garage rebuild. Bottle brush honed and new crank/rod bearings. Clearance on bearings (plasti-gauge) were in spec, but I only checked in one spot for every journal.