Wow, hello all you lovely tall women! I didn't know so many of us were this height.
Now, OP, I can't really answer your question about being a size 6, because I haven't worn that size since elementary school. But, since sizes have changed through the years, I used to wear a 14 at 180 and it was tight. Now I'm 210 and wearing 16's and some tight 14's. I guess when I get to 180 I'll have to see what size I can squeeze into?
But . . . going by the loose rule that dropping 10 pounds means dropping a pants size, I would think you could fit a 6 at 158?
267: Highest known weight
242.5: Weight on dd's 1st birthday
213: Weight on day I delivered dd (Whooshed past on 7/6/10)
200: Weight on day I went home from hospital after delivering dd (MET!! 1/24/11)
180: Lowest weight ever as an adult
170: Initial goal weight (subject to change)