Hence the reason that we're only left with 1/4 quart in the pan turning over 6k RPMs...

And that's with 6 full quarts in the thing!
The oil SUPPLY system is great- It's the RETURN passageways that are a bit... Um... Slow?
I used the brand new 3L oil pump that came on my otherwise brand new 3L block. Indeed it is very stout. I took it apart to ensure there were no metal shavings from when the piston let go, and put a thin film of grease on all parts when I put it back together (quicker prime, since the motor was bone dry when I cranked it), using loc-tite on all the screws.