A couple of mysteries solved.
1) the bolt on the side that I was asking about goes into the coolant side of things, not the oil galleries. With the water pump already off, blowing air resulting in a hollow sound and air escaping through the large opening for the water pump.
2) a week or two ago I was asking about replacing the oil line in the lifter/push rod side of the engine. I used Mr. Google on the interwebs to find a company that sells a NOS oil line replacement kit. The photo below is the old line at the top and the box and the kit on the lower half of the photo.
The new kits uses compression fitting versus the flared ones on the engine. The next step is to ensure that the thread pitch on the two connecting fitting are the same, they look to be.
