You are a giant, and line seems to make skis on the softer side of things. Some kid said rockers...I would not recomend those for a first twintip, the change to twintips is big enough.
The older brands come to mind when I think of a stiff ski, and when I think of a beginner ski, I think of the Fugative (now Extremes) made by K2. I would look into those in the longest size possible, because with your height and racing background, coupled with the closer-to-center mount, you will need a longer ski.