I know it is comparing apples to kumquats, but the factory specs for the GMC six cylinder engines call for a minimum of:

40 psi oil pressure at 2750 rpm on a new or newly rebuilt engine
25 psi oil pressure at 2750 rpm on a used engine

5 psi oil pressure at idle rpm on a new or newly rebuilt engine big_eek
2 psi oil pressure at idle rpm on a used engine cantlook

Oil recommended for use between 32 and 110 degrees F was SAE 20

I measured the oil pressure relief valve at 58 psi.

'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.