Low Oil Pressure & None @ the Rockers

[72 Cheyenne K20]

Hey Guys & Gals,

I bought a 1976 GMC K15 with the factory 400, TH350, NP203 about 3 months ago from a guy in Reno. It runs, drives, and stops pretty well. No real issues other than low oil pressure.

Factory gauge reads 30-32 on cold start
after warm up just off of fast idle reads about 25
after warm fully 12-14

It responds when the throttle is pushed but never goes higher than 30 at a steady cruise at 55-60 mph.

I've read posts here and online research and have done the following to diagnose:

New Wix 51061 filter, 15w-40 oil, and a mechanical gauge installed and still same or worse results. at hot idle with these done it had about 5-7 lbs of pressure on the mechanical gauge. (I also notice that it took a really long time for the plastic line to fill with oil to get to the gauge)

So, I bought an oil primer tool and tested it today with valve covers off. I'm getting zero oil to any of the rockers and roughly 35 lbs of pressure on the mechanical gauge on a wide open 3/8" Dewalt drill. Not sure if it matters but I do have the harmonic balancer mark set @ 6am.

It takes a few seconds for the gauge to read any pressure and I'm also hearing a rhythmic kinda whining noise other than the drill turning.

Please send your thoughts on what you think.

Thanks, Scott