oil pressure, I'm still buffaloed

There are two plugs to look at. The easy one is the drivers side oil gallery. Take the distributor out and look if it is threaded in at the back of the gallery. The other one is above the rear main cap.It can be pushes out from the oil sending unit hole.But it is installed thru the hole in the block above the rear main cap. To install use a punch and hammer, it must be seated solidly. If the machine shop hot tanked the block , this plug should be repaced.