Oil pressure gauge question

[GMtrucknut!!]

I am using the OEM oil pressure gauge in my 55 2nd series and when cold with my rebuilt engine it pegs the gauge upon startup when hot it goes just above the halfway mark. I am running 10w30 motor oil . The crank has been ground to 10/10 clearances were .0015 on the rods and .0025 on the mains . I am running a Melling M55HV oil pump. Does anyone else have this and has anyone every compared their oem gauge to another gauge which has increments marked ?

[capnduane]

My stock gauge shows half way between the center mark and the hi mark when driving. It shows halfway between the low mark and center when idleing hot. This corresponds to 15lbs hot idle, and 40lbs at driving speed on my aftermarket gauges.