Does the Graco Nautilus really hold children to 65 pounds in harness?

This is my question... For my kids build will the Graco Nautilus really hold them to 65 pounds in harness? I've read sooooooo many reviews and studied pictures and I still don't have an answer. My kids are apparently a little bigger than most... not in a bad way. My son is 4.5 yrs, 45", and 55#. My girls are each a little over 3 yrs, a little over 39", and 40#. I realize that my girls will not be as big as their brother at his age (nor does he need a seat, he's in a Regent) but I think I'm going to put my son in a Nautilus at the store to see if he fits harnessed. If he can't fit harnessed then I feel as though I'll be forced to buy Frontier 85.