oil pump failed

Oil pumps VERY and I mean VERY rarely fail "all by their self". I would be looking for a piece of "something" in the pump that locked it up. Trash that's gotten wedged into a main oil galley, or something "like that". Did you ever see GOOD oil pressure on the gauge? If not, remove the distributor and check to make sure the pipe plug is installed in the block in the main oil galley on the driver's side. If that's left out, you'll get very little to no oil pressure.