200lbs, 300 ft hill, assuming you know what to do with a ski,
Lazer SX at 178
Lazer Cross 176 cm, or Lazer Cross pro (if you really know how to get the most out of a high performance ski)
171 is is about the right length in a SL ski, you need a little longer for GS.
It is true that you will need to waste a bit you your hill getting up to speed with the longer radii, but there is no helping that if you want to make some good gs-ish turns as opposed to SL turns.
Getting a gs ski that is too short is not the way to go. Neither is getting a softer flexing gs ski (been there done that).