Hi volume oil pump

I dont like electric oil pressure guages. I used one once years ago - an autometer guage (read: not junk). Oil pressure readings varied depending on the load on the charging system. Maybe theres a fix for this - I suppose a capacitor in line might help. Anyway, I'd check it with a quality mechanical guage before doing anything to the engine.

If that checks bad, then there are a number of causes:

Stuck by pass valve in the pump

Faulty pump, excessive internal clearances (worn out)

Excessive rod and or main journal clearances

Improperly installed oil gallery plug - the one above the pump inside the block.

Plugged oil pickup. I've seen first time engine builders use too much silicone sealer on gaskets and have the silicone excess come loose and find its way into the pickup. Had a friend of mine do this - his pressure was fine until a few hundred miles then the silicone came loose, we found his pickup full of silicone "worms". Lots of fun pulling the pan in the car to fix this.

I've not had issues using a high volume pump, so maybe you want to look into one when you reassemble the motor.

Good luck with it, and dont drive it until you figure it out.