I believe (not 100% confirmed because the Milodon website is a little unclear) The stock capacity of the 5.7 and 6.1 motors is 7 quarts six in the pan + 1 in the filter. The Milodon oil pan PN 31000 has a 6 quart capacity, whether that is 6 in the pan +1 in the filter or 5 in the pan +1 in the filter is unclear.
Milodon also sells an oil pan PN 31003 that has wings that Appears to increase the capacity by about a 1-2 quarts. Milodon doesn't even list an oil capacity. GRRR. So this one could be 6+1, 7+1 or even 8+1.
As for putting 10 qts in your car upon start up. That seems like a lot, but who am I to argue. With a remote oil filter and perhaps oil cooler ten quarts is probably not unrealistic. From your description it sounds like the Milodon pan PN 31000 has a capacity of at least six quarts meaning 6+1. Which would confirm your statement that the Milodon Pan is close to the factory size.
One thing to keep in mind, particularly for those who plan to run a flying mile or road race the car, is that oil coolers, lines and remote filters DO NOT INCREASE the capacity of your oil system.
Be clear that extra filters and/or coolers do not add any oil to the engine's sump capacity. What oil is added to fill them always remains in that device and is not an additional supply for the engine's higher RPM needs that is the job of the larger sumps.
So I would agree with Rat Patrol that those planning on spinning the snot out of their motor should invest in a higher capacity pan. I'd get at least the 31003 Pan.
Regards,
Joe Dokes