Brian, I don’t think the image you posted is the same pump that Mike’s car is using, although I agree with you that two bolt holes go unused with his application. The pump in the image appears to be a standard rotation long pump based on the single bolt pattern hub, what appears to be the smaller 5/8” shaft, and the included gaskets.
looking at the back side of Mike’s pump and the PH-569 cast into the front on early castings, I’d say he has the standard rotation short pump (PN M-8501-E351S), which requires an unusual gasket between the pump and backing plate. The gasket part number is Fel-Pro 35214, and it’s very difficult to find, but it does come included with the short pump.