To answer your question yes you can over fill a lower. The lower needs a small void area for heat expansion. Early 3L Mercs have been known to only put 32oz in the lower or the oil can push the top seal out. I have found some motors that you can not let all down for correct fill check and I will refer to motor spec`s for lower units capacity.
“The world will not be destroyed by those who do evil, but by those who watch them without doing anything” Remember what He has done and remember that He is not done yet! GOD IS GOOD