Re: No oil pressure at idle
That's great news however I suspect you will be missing the plug from the rear of the block also. It probably didn't leak yet due to lack of oil pressure.
I would slip a piece of stiff wire (A piece of windscreen wiper stainless steel backing works well), down the oil gallery from the front oil gallery hole and measure the distance to the rear, If it is the same as the block length the plug is probably missing.
I have attached an rear image of the cylinder block for you to see the location.