How long did you run the car with the knock? I replaced the oil pump seal one time on my old 90 sc, didn't prime the system up or anything, knocked for the first couple seconds it ran before I shut it off. Started it back up after a couple prayers and it was gone just as abruptly with oil pressure. Scared the crap out of me. Proper way would be to get a hex-shaft to put down in their and spin it counter-clockwise with a drill until you feel it build pressure.
Chris