I’ve wondered about this myself.

How far below the block rail is optimum oil level, and is that with or without a windage tray?

Sees to me that as long as the level IS below the tray it would be good as that level will drop when engine is running but when I checked mine I was able to fit an absurd amount in the pan (like 8 quarts) before reaching the tray——-so I abandoned that thinking.

IIRC 5 quarts barely filled the sump.