I almost suggested Quentin Malachi! I love it.
I think it could be a winner, but I'll suggest a few combos anyway to see if there are any that really grab you:
Quentin Bartholomew
Quentin Abram or Abraham
Quentin Isaac
Quentin Jeremiah
Quentin Matthias
Quentin Phineas
Quentin Tobias
I also really love Quentin Josiah. We can't use Josiah as a fn since we have a Josephine. I'm not sure if it's just as unusable as a mn.
Oh, and I love Nina as a nickname for Antonia. Antonia "Nina" Russell sounds quite glamourous.