Consider the extra oil as insurance. Depends on Hp of engine and if you are running an oil cooler or not. Other factors is how fast does the oil get back to the sump, do you make any hard turns, pump pickup location in the pan, and a bunch more things I cannot think of. I can say on a 540BBC I was messing around with oil levels with new Dan Olsen oil pan just to see how well it contolled the oil. I took oil level down to 4 qts in the pan with no pressure loss. After a couple miles of straight line running at about 40mph the oil temp would get high and then pressure would start to drop. Do not think it is a great idea for everyday use so I keep at least 8 in it.
I did a mild build to an open bow 21 Eliminator a few years ago.
I bought a 12 qt Milidon pan and it use to airate the oil when full.
The more rpm, the worse it got.
I took it down to 10 quarts and it was the same issue.
I don't understand why you would run less oil in a large pan because the pick-up will not be as well submerged. This would invite oil starvation in a sloshing condition.
I changed pumps, changed pick-ups,& pickup clearences. I had that engine out 4-5 time.
Got so sick of it, I put the 7 qt pan back oin and sent the 12 qt back to Milidon.
My current ride has a big pan so I am "for" the application that can provide more oil capacity. Oil is difficult to cool down so having a larger capacity will reduce bearing temps. for a longer time.
Just sharing my experience in case you decide to change your pan