When to worry about engine noises?

FWIW I've been running Valvoline 5W-40 "European Formula" in my roller-cammed 360 for at least 6,000 miles now, no noises. My hot oil pressure at idle is around 15 psi which is on the low side but I have external oil feed to the rocker shafts along with hollow pushrods and I'm fairly certain my valvetrain is getting more oil than it needs. I've been meaning to make new rocker shaft hold-down bolts with a smaller hole to restrict oil flow a bit more.

I picked that oil because it's fully synthetic, I like the viscosity spread, and it's approved for certain late-model European engines (both gas AND diesel) that put high stress on valvetrain parts, oftentimes with flat cam followers. This particular engine has a roller cam anyway so I also don't need zinc, however I believe there are modern additives (moly) that serve the same purpose and do a better job. Would I take that gamble running this oil in an old-school flat-tappet V8 as opposed to something like Penn Grade or Schaeffer's though that does have zinc and is designed for older engines? Probably not...