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.
I could be wrong, but I think you may have the answer to the low oil pressure question. I'm not trying to pee in your Cheerios, but a garage 'refresh' is risky on an engine you haven't heard or seen run.