Hi.
For your size the Fluid Nemesis Medium should be good if they are available in your area.
I am slightly taller 6'1 and weigh 167pounds, I fit in really comfy. With your weight you should be floating happily, you might find some flatwater moves tricky, but this is easily overcome with good technique. For a review on the kayak have a look at Adrian T's page:
adrian.playak.com/index.php?option=com_c...=view&id=80&Itemid=5
Happy paddling
d