[Rich Biebel]

This engine has something way more wrong than these minor things like blocked filter bypass or a partially blocked passage under the cap.

If it striped up bearings just running for 1/2 hour and not on a dyno or at the track it is more than a minor issue.

So far its been blamed on

Pickup location
To much oil in the pan
Grooved lifter bores used with EDM hole in lifters
To much oil up top
Rear plug slightly out of position

This is a relatively low HP and RPM engine and one that generally is a trouble free engine design as it comes from Chevy.

A good clean block with no blocked oil passages.
A good line bore and crank sized to give you lets say about .025"clearance on mains and rods with a good thrust clearance as well
Good quality bearings
A good oil pump and pickup and filter
Clean assembly of all the parts....

Oil pressure could be across a pretty wide range and still be fine...
Oil viscosity and engine temp. changes that a good bit but lets just say some sort of pressure even at lower rpms and a warm engine.
30-40lbs hot at an engine rpm of lets say 1000....

Everything above is up to the engine builder....parts, bearing clearances, oil and so on..

To many cooks spoil the pot...and even though lots of info and tips may be helpful it has not solved this engine riddle.....

Something is clearly being missed.....something way more than minor....

Go back and look at the block and the crank more carefully....