Pay close attention to what's going on when "tuning" oil quantity & viscosity. Can't give precise numbers due to individual variations. If you lose excursion (travel range) then you're hydrolocking and need a few CCs less oil.
With the caps removed, the fork bottomed-out you should be able to see the oil...and use that to get the same fill level in both.
With the caps removed, the fork bottomed-out you should be able to see the oil...and use that to get the same fill level in both.