I was wondering the same thing a while ago, and spoke with Earl at Dove's. He said to insert the dipstick in the engine with it upsidedown with the pan off. Stick on the windage tray and mark the stick ~1/2" below the windage tray (above when upside down) this should be the desired level when full. I then add
oil to the engine until after it is run (filling all the lines cooler, etc.) until it hits that mark. Takes out the other variables such as
oil line length,
oil filter capacity, etc.