I understand what you are saying. Here is my current thinking on this - what do you trust - a written specification or a physical measurement? Obviously, 8-quarts is satisfactory as that is what the factory recommends and warrants. But, what if you could put in another quart?I would never add a quart just to satisfy the dipstick. If you change the oil yourself and you use the recommended amount (7.7 or 8 quarts in your case) wherever the oil level is on the dipstick, then that is your full line...
What is the downside? If the oil is too deep in the pan, the crankshaft will catch the oil as it rotates and whip it into a frothy frenzy. That's probably not real good for the oil. In addition to impacting efficiency (mileage) from the additional drag, there is maybe the possibility of sucking air in the sump pickup and loosing oil pressure in an extreme case. All of these are reasons why racers use windage trays (my understanding). Typically engines are designed with some headroom between full on the dipstick and contact with the crankshaft.
What is the upside? My opinion - the upside of another quart of oil would be that, with an additional 12% oil capacity, the oil would be doing that much less "work" - the oil would be cycling from the pan through the engine fewer times. There might even be a small impact on oil temperature, but I'm not convinced on that.
As a point of reference, the oil capacity for the Mercedes V6 3.0L turbo diesel used in the Sprinter is 13 quarts. The Sprinter 4-cylinder 2.1L diesel takes 12 quarts, Obviously a different engines, but most diesel engines are designed with high capacity oil sumps for a reason.
I'm becoming less of a rule follower as I get older. If the engineers at VM Motori were capable of designing a dip stick that accurately represents the oil level in the engine, then I see no downside to adding a additional quart to bring oil level up to the full line. Just my opinion.