What is the normal oil pressure for a stock 350 in a 81

Believe it to  be 45 PSI at 2000rpm The idle pressure should increase with RPM to indicate pump is working

My 82 runs about 40# when cold.  It does not take a lot of oil pressure to do the job really.

The old racer's adage of "10 psi for every 1000 rpms" is a good number when hot. You should have around 30-40psi, anyway, at idle, when warm. Unless you have a mechanical gauge, I wouldn't trust the electrical gauge to be 100% accurate.
Truth is, you don't really need a lot of pressure when running....as long as it rises with rpm, that's a good sign. What you need at higher rpms is more volume, since the spinning crank causes centrifugal force to throw the oil off the crank/bearings fairly quick. More pressure won't solve that, but more volume will.
Higher pressures will actually slow the engine down, and cause more stress on the pump, the cam gear, and distributor gear & shaft.

To All, The system now and for a long while being used for the electric fuel pumps in fuel tanks have a internal pressure for shut down when loss of oil pressure and it is set at 9# as does aftermarket systems like the one Mr. Gasket has to tie into the oil/fuel system. I have used on VETTERBOBS Vette, a set up for installing electric fuel pump eliminating the mechanical pump and in the systems manifold is a sending unit that when it sees only 9# pressure cut off power to the electric pump and shuts down the engine to keep it from tearing up bearings etc.Also supposedly a safety if you roll the car and end upside down and oil is away from the oil pick up and will shut down the engine and reducing chance of fire....In essence the engineers decided 9# was when it is not enough oil pressure.. Kudos to Mr Adams on his statements regarding the pressure vs volume..He is very correct that the higher pressures can be more hazardous than high pressure and low volume.I have found that in racing and even hard street driving,that you can lose suction in the oil pump with a high pressure pump,due to pump creating a vortex and funnel up a foam causing a loss of oil to the upper region of the engines. Melling has two Chevy pumps high pressure (55lbs.output) and the stock OEM of 40#..The 40# is what you want to use.. Have a great day...