If this a frame that uses a traditional external cup headset, isn't some of the stack height you mention for the King HS already factored into the design of the frame, especially the lower cup? I would think you only need to worry about the King if its stack height is significantly different from another HS you might use or that Colnago designed the front end to use.
King is one of the bigger headsets as far as stack goes (adds 30 mm I'm told) but apparently not so different from others that it matters. Yes, of course factored into frame geometry.
Colnago has relatively shallow head tube angle and thus relatively long front center measurement when compared to an average bike with the same top tube length. If I was buying a Colnago, I would expect to have a top tube that's 5-10 mm shorter than my current bike (and a suitably longer stem) in order to keep the wheelbase and the weight distribution between the wheels where I like it.
I'm actually of a similar height to the OP, and I would personally be looking at sizes 56 and 57 with a 130-140 mm stem.
Very good observation on the head angle. Aprox 72.5 degrees in my size. Compared to the more standard 73 and occasional 73.5 (my ML Altum). I think a longer wheelbase (with possibly quicker steering) is exactly what I am looking for. Assuming equal fork geometry, I find 73.5 head angles result in steering that is just a bit slower than I like, and require more overall bike lean in extreme cornering situations. I know why Parlee did this and it has it's benefits. The average doctor or lawyer that buys a Parlee can cruise down the street in a nice straight line without paying attention. Phenomenally stable and predictable handling in any situation for such a light, stiff, quick, tossable bike, but to me it feels a bit neutered in the handling department. And the toe overlap with my big feet is silly.
When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.