Forget seat tube based sizing - effective top tube, ie B in the above geometry, is a more useful number. As per CC, you are looking at a 560mm effective top tube and a 110mm stem.

Even allowing for a slightly smaller reach for a more aggressive triathlon-oriented fit (eg, my own reach is a good 25mm lower than what is recommended by the CC calculator, with a 5.5" saddle to handlebar drop), a size M with a 535mm ETT might be a bit too small for you possibly?

V.