I am just under 6' and weigh 190-195 without gear. I was I the market for a new creeker and went with the large shiva without demoing. I was concerned about the size when I ordered it and am glad I got it. At your size I would recommend the same. No doubt it seems that boats are getting bigger again and the shiva gives me a lot of confidence, because quite frankly, there is a lot of boat out of the water. I usually carry extra gear including video camera, safety, lunch, etc. So far I have paddled down the Upper Animas and Vallecito (both at lower flows) and really liked how it handles.
As rg5 mentioned, the swede form of the boat does allow you to keep a nice vertical stroke close to your knees and hips.