If it is pegging the gauge, then it is probably faulty. Doubt if your oil pressure is that high.The sending unit may be incorrect.
If you or the previous owner replaced the gauges from the set that had idiot lights, then you simply have the wrong sending unit.
Replace the sending unit first. It is located by the distributor cap.
Like I told you in another thread, take off and when you are to shift in 2nd, put it in 4th instead. Then gun it. If the engine revs and speed doesn't go up or barely goes up, then your clutch is slipping.