I welded on a commercially available adapter that takes standard oil fitments. I also replaced the grub screw with a commercially available connector. All parts are available from all oilcooler and pipe suppliers. My gear is EARL'S performance plumbing. The hole to be blocked is the one through the main pump drive gear. I tapped the hole and fitted a grubscrew with loctite, I intend to put a spy of weld on to secure, better safe than sorry. I have posted photos a long while back. My garage is a bit of a shambles at the moment so it may take me some time to dig the cover out, I will post photos as soon as I get them. As the other poster said you could drill and tap the cover, not sure of the thickness from memory but this could work.
Ralph