I put a 62 - 235 high pressure motor in my 46. I used a after market oil pressure gauge for the block, which reads 40. And hooked the factory gauge to a fitting at the top of the head that reads 15,right in the center. It also helps in knowing what is going on, I broke a push rod a few years ago and the factory gauge hooked to the head went to 0 and the block gauge stayed right at 40.

1946 C.O.E. with a Holmes Traffic King Wrecker