Ah given your size you're probably gonna be in perfect shape.

The cobra is pretty awesome, I've been liking it quite a bit. Just make sure you've got something to stop the wind (I've got a softshell vest that does the trick), because wind rips right through the thin merino.

Once you cure the wind, though, it is deceptively warm. Poly + Cobra + Windbreaker is good into the 30's as long as you keep moving.