As mine is in the dining room!
I have a medium and it is roughly 74cm to the rails. 78 to the top of the saddle.
With the 400mm post I have 1cm of leeway. I put a 150mm brandX dropper on and there is plenty more.
It feels right. I have come from a medium Parkwood which was a little shorter but had a longer seat tube.
I’m about the same height as you and leggy which often makes bike sizing tricky. I probably could have gone for a large as well but it was only the short seat tube that made me doubt the medium. I would have been interested to sit on both but it wasn’t an option. Knowing I was happy with my Parkwood for both XC and trail centre fun I went with what I knew.