If I was dropping $3500 (or even $500 for that matter) for a new bike, I would insist that the shop order the right size. If they wouldn't and instead tried to put me on what they had in stock, I would walk out.
Dude, you ride a 56cm road bike?!? I'm 5'8" and *I* ride a 56cm!!! And no, it is not too big for me. I can't imagine someone 6'4" trying to ride my bike!