Regardless of what it's for, the process and parts are the same. Unscrew the center nipple, and put in an AN adapter. That would probably only cost about $10-15, and summit or jegs will ship it right to your door step.
The real issue is the other hole. If you want to use it or seal it, it needs to be threaded. That requires engine removal and, at least, partial disassembly. Since there's no
oil pump, you could probably get away with using a compression cup - like a small freeze plug - in each end of the passage. I wouldn't be comfortable with that, but you could do it.