bullseye - it is difficult to answer your question, since your actual installation would dictate what, if any,
oil drains out of your cooler.
FWIW, I doubt any of the
oil in the cooler itself would drain, might get a bit out of the lines.
The only proper way to define the "correct"
oil level in the pan is by measurement - static oil level should be around 1" below the crank counterweights at their lowest point I believe. Mark the dipstick to suit.
I hope someone else chimes in to confirm/alter my 1" below the crank figure. This is an empirical "guess" on my part.