Follow up:
I replaced my oil pump w/ a melling m295HV, and pickup tube o ring.
I did some checking during tear down:
All Bolts were secure, no concerns with anything loose or out of torque.
Oil pump and block mating surface were in good condition with no pitting or erosion
Pickup tube o ring was soft and pliable, fit tightly. Screen was clear and free of any varnish. The tube was inspected for any cracks or other distortions. No concerns there.
Oil pump gear tolerances were 0.004" consistently across the gear set. Neither housing nor gears showed any marring or scoring.
High pressure bypass spring was visually intact with no distortions. I don't have the equipment to measure the spring rate so I can't glean any info there
The bypass piston showed some marring along its length in one spot, roughly 20 degrees along its axis. All other areas were in good condition and showed no visible signs of wear.
My suspicion is the piston was binding up on something. My fingers are too large to fit in the cylinder to feel for any flash or other machining errors.
When I replaced the pump with a high volume high pressure(spring) unit:
idle pressure when hot increased from ~29-33psi(fluctuating) to 48psi consistently
2k rpm hot oil Pressure increased from ~40(mean of fluctuations) to 65psi
Redline hot oil Pressure increased from 65(? Pressure swings too large to get any reasonable reading) to 110psi.
Oil used is Mobil 1 0w30 ESP.
I'm quite pleased with the outcome and am confident in marking this solved.
A few notes:
With higher flow, it's advisable to use a larger oil filter with more internal media to avoid the filter from going into bypass excessively. I use a Fram Xg3675 - a longer filter with synthetic media and a thick housing.
With 110psi, use a quality filter with a thick housing. You don't want it to blow out.
the job takes around 7 hours to complete, including supporting gaskets such as the oil cooler blockoff plate, which could be prone to leaking under the extra pressure if they're old. Everything will drio everywhere and you will make a huge mess. Bring lots of shop rags and a few crappy towels. I allotted myself 4 days. Day 1, let coolant drain, day 2, remove oil pan, let it drop out, day 3, do the job then let the rtv cure for 24h. Day 4. Fill everything up, test drive, and verify work
You will need a harmonic balancer puller and installer. It's press fit. The rent a tool installer from O'Reilly works if you get a 3" longer through bolt, otherwise it won't reach into the crank.
You'll need a means of aligning the front cover concentric to the crank shaft. I used a tool from sac city corvette. I found that threading the bolts into the front cover, wiggling the top from side to side, then moving it to the middle of the 2 limits of movement provided satisfactory alignment.
The front cover, gasket, and block surface all sit flush with one another. Don't forget the RTV on the corners!
A u joint and 1/4" ratchet with appropriate extensions is a life saver
You will need 2 people to remove, then torque the harmonic balancer. Holding the crank still can be accomplished by removing the inspection cover on the bell housing and inserting a medium sized pry bar into the flex plate. Mind the pry bar is kept square to the welds to avoid distorting it
The pickup tube o ring is a tight fit. You'll need to lubricate it and apply a fair bit of force for it to seat in the oil pump. The retaining bolt will NOT suck it in.
Uhh... That's all I got. Hopefully this helps anyone stumbling across this thread. I can do a descriptive write up if interested. No pics though
