I have decent oil pressure gauge. Although I havent put it in yet(too scared). Last time when I was installing oil sender, the old sender snapped in two. My attempts to remove the stump caused engine failure . Spun big end bearing because by some farking oil sender fragment . Engine was jammed only 990km after full rebuild . I still get bad vibes. Motor has lasted now 5000km after second rebuilt.
If I wanted to go through "...measure/rip pump out/install with shim/measure/rip pump out/install with new shim..." hell, I wouldnt be asking this in first place .