Did you get it taken care of? I removed the oil pump on my 83 without any problems. Just the 4 bolts according to the Haynes manual. Something could be binding up with the spine gear (the spline gear for the timing is stabbed into the oil pump and a connecting rod links it to the distributor. Just a note, make sure to set your engine at #1 TDC and mark the position of your rotor bug before removing the oil pump. I made the mistake of skipping that step and it took me several tries to get it set back in time.