#23
in this diagram? Wow, that's a tough one. I'd say it depends on how far you want to go with the car. A machine shop would be able to bore out & press a new part in with little trouble, but taking the head off for such a repair is a lot of work.
If it was my car, I'd consider using epoxy to secure a tin fitting like the heater core lines above. Or maybe an air compressor fitting of some sort? You could tap some threads into the head & possibly use a fairly large male threaded fitting (1/2" ID?). I'm unsure of the proximity of oil passages in that area, but I'd guess you'd be safe.