You didn't state whether you have electrical or mechanical gauges. If you have an electrical temp gauge, you may have a defective sending unit or a mismatched sending unit or conceivably a steam/air pocket where the sensor threads into the mainfold. Check the resistance of the sending unit at operating temp or check the part number and verify that it's the correct one for your gauge.
90 pounds of
oil pressure seems very high, especially if you still get that reading once the engine come up to temperature. If the
oil pressure gauge is electrical, you probably have a sensor issue similar to the temp one. If the gauge is mechanical, you either have a defective unit or the
oil pressure relief spring is wrong.
There may be other causes too but these are some of the most common problems.