I didn't think a sealant was necessary, but when looking for torque specs, the Hayne's manual said to put a thin layer of RTV on the gasket. I had never done that before and I have seen other things in these manuals that have made me scratch my head and go huh? I can see using some hi tack, so I will use some. The Melling gasket kit that I've got didn't come with the large O-ring, just the gasket and O-ring for the neck of the pump.
That is what you need, the two O rings in the pump should be in the pump, not needing to be installed in the pump before installing the pump
I have used Gasket cinch on the pump body and pump gasket to hold the gasket in place while installing the pump, I did not use silicone gasket maker type on the pumps or gaskets
The new Milidon race oil pumps now come with O rings only and no gaskets
That has worked very well for me on the last 4 or 5 race motors that I used Milidon external oiling systems on
Very Well