Oil reserves

Good question.
It all depends on how good your drain back is in the block.
If you have a high volume oil pump, it becomes more of a concern.
My guess is that you would have at least 3 quarts in the pan at that R.P.M. with the rest in the engine either coming or going.
As your R.P.M. increases, you're at the mercy of the drain back so you don't ''suck the pan dry.''
That's when high volume oil pumps and higher volume oil pans come into play.
Here is a decent article to read on the subject.......
Around and Around - Where the Oil Goes in Your Engine