I never had the luxury of having a inspection scope while with dealership. Bought a cheap one a few years ago but pretty much useless. I did a lot of pressure testing of individual cylinders. I like that test to see if there is leakage, which cylinder it is in and also detect leaking rings, valves etc. Takes time to do it of course.
As for oil pressure, I don't know what the engineers reasons were but that engine has huge crankshaft and bearings and a lot of them for the cubic inch of engine. My old Chev was 14 psi, but with the dipper on the rod picking up the stream of oil directed at it from the tubes in oil pan , who knows how much pressure that rod bearing was absorbing.