Why would u think he was making a pointed remark to Lee? I think he was talking about the Founding Fathers.
"A score is another way of saying 20, so Lincoln was referring to 1776, which was 87 years before 1863"
Henry Lee was Revolutionary War General as well as the father of General Robert Lee. He truly was one the fathers who brought forth upon that continent a new nation. The question is if Lincoln was appealing to Lee with a direct and personal reminder.