My 396 has similar oil pressure, about 80-85 cold and drops to about 65-70 warm. I never had a problem with the sending unit leaking or failing. My oil pressure might drop to 50 at idle, but goes up as soon as you touch the gas. It is more pressure than I had wanted from the melling pump. I have pulled the motor anyways, to replace it with a 454 so I don't damage the #s matching motor.
Garnet Red 69/SS396/TH400/355 Posi
94 HD Dyna Wideglide