My 1969 340 Swinger, that I sold in 2001, had low oil pressure at idle, when the car was fully warmed up. Most of the time I had 10-12 lbs. at 750RPM idle, fully warmed up. One time the car was idling at 650, and the mechanical gauge read 8 lbs.!

The red oil pressure warning lamp faintly lit, but I jacked the idle to 950 and the lamp never lit again.

One area I was told to check but never got around
to was the pump pickup clearances, to the depth to the bottom of the pan, the angle of the tube, and the mating surface at the attachment point.

Engine never ticked, and the oil pressure increased as early posters stated, in a linear fashion to 50/60 lb.s at 60 MPH cruise.

The engine ran like that for 2 years, and I put a couple thousand miles on that engine, ran like a scalded dog!

The new owner also never had a problem, and he subsequently sold the car, and now ... still no problem!

Drive it and don't worry!