Uwe, I have a 351 Cleveland and run about 30 - 40 PSI at Idle and over 80 PSI at 3000 + . My engine build tolerances are tight and I used .125 inch restrictors. I also ran a SS bypass from the front of the engine to the rear. This line runs from the port next to the
oil filter connection back to the rear
oil sender port.
I have a Melings HVHP pump with a billet drive. My Dist gear is the stanard one on a Mallory Unilite unit.
When running a stanard pump, I saw many Clevelands drop to 25 PSI, a bit to scarry for me. That is why I opted for the HVHP.
You can, just as a test, put a crank-drive in the dist. hole and run the pump up. It should be a resistance to get 20 to 30 PSI, but you can try.
Just my $0.02