For Christ's sake, just buy the damn stock bike and upgrade from there. The stock bike is cheaper than a $320 temporary build kit.
I'm the same height as you. Get the 57cm unless you want to run 3 miles of stem spacers.
BTW, threaded forks are inferior to threadless. Stick with threadless. If you have a vintage or NJS frame, then I could understand wanting threaded to match the look. But its just a cheap chromo frame you are building up here. Stick with what works better.