you have to remember that skiing center makes the skis shorter, so 176 should be perfect centered. A little long if they were at recomended but centered you could even jump up to the 181s if you wanted, but it is all about if you ski agressive and what you prefer. In general 176 should be good though.
But I have 2 pairs of centermounted 171's (addicts measure shorter than the invaders) and they feel kind of short of me and I'm 5'8/5'9 so 176 might be good.
i hav ethe same height and weight as you and i ride on 171 invaders, which i got last year and i should have gone for the 178. go bigger. in the beginning of the season they felt real short but i got used to them. it depends on what you want.