When to worry about engine noises?

Glenn Radford said
I recall a U-Tube video of "Nick's Garage" where he couldn't establish over 25 psi at idle in a 318 he was trying to dyno test. He eventually established that the engine had at one time been fitted with AMC style hollow pushrods, which drained off oil pressure to the point where overall engine pressure was too low.
Not sure if this applies in your case, but may be worth considering.
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THIS RIGHT HERE, is the reason the internet is able to spread bad information. The engine you are referring to, had a crankshaft ground .010 under on the mains, and the "engine builder" installed std bearings without checking clearance. It had ZERO to do with the lifters or pushrods. Oil is metered through the lifters, and it's not just a open leak.