High Beam/Turn Signal switch issue?

[JPSmit]

50 PSI at reasonable revs seems OK, seems like the Oil pump is not he issue
However, 10 PSI at idle seems a little low. Personally do not like motor to be less than 20-25 at idle when hot.
Just because it is easy, have a look at the Oil pressure relief valve. Look for any signs of wear such as a groove or such in the piston.
Leakage through the relief valve could cause low PSI at idle
You could turn the motor by hand with the valve out to "flush" the seat of any possible debris.
If there is no problem with the relief valve then I am afraid it is the bearing clearances. I know it can be done but without a proper lift To raise the car I would not try to change bearings with the motor in the car and even then it is not a simple job.

Don't forget this is the 1500 "big block" so the pressure is actually pretty normal. The oil pressure relief valve is also different. I tried the 1275 solution (stretch the spring or add a ball bearing or some such voodoo) and blew the oil filter right off the car. I am still cleaning up from that mess.

 

[Joe Schlosser]

Yes the pressure relief valve is primarly for controlling the top end pressure.
However if it is scored it could be letting some oil bypass at the low RPM. With higher Pressure and volumes at upper RMP this leakage might not matter.
I agree that it is most likely bearings but as I said it is a simple thing to check before a teardown.