Cranking pressure cold is 170. It has forged pistons, so I will try it again hot, there might be some expansion going on. Fuel is 91 Chevron with 10% ethanol, One can't get better at a pump in Ca.
The OBD-I Magnum 360 V8 in my post above has compression test results:
155 psi warm
170 psi warm with a shot of lube oil
Check all the “accuracy” suggestions in posts above.
One trick for spotting pinging in a particular cylinder that I learned that is seldom posted:
Buy a “fires in oil” sparkplug adapter and try it cylinder by cylinder.
These adapters move the position of the spark away from the center of the cylinder.
This is like retarding the ignition timing of that cylinder alone.
The adapter will not make a difference if the pinging is caused by carbon deposits in a cylinder that glow red hot at wide open throttle and high rpm.
The testing goes faster if you first use 2 adapters at a time, then switch to 1 adapter.
There is also an “opposite” individual cylinder ignition “advance“ trick:
Use an Iridium tip sparkplug with a wide gap one cylinder at a time.
you dont know until you try something, every combo is not EXACTLY the same, I to am at sea level& have fought & learned how to deal with detonation, somewhat LOL 
. If the engine IS the lower compression stock type cam build, then that sets up for a different solution to the problem. assuming the balancer TDC mark is correct then i'd say contaminants in the intake charge.