I think that the previous suggestions in this thread to go fatter are right on the mark. Few people (no matter their skill level) are always in situations where they can carve every turn, particularly, with the long radii and higher speeds that stiff, not-so-fat skis favor.
At your weight, wider skis (90+ mm) will smear turns much more easily, many will be superb in crud, as well as quite usable in more packed conditions. As I have said in many previous postings, for folks of my weight and above (ie, 215 lbs), the only purpose I see anymore for low-mid 80's skis is when you ABSOLUTELY can't take two pairs and know you are going to encounter lots of rock hard snow as well as soft snow. For all other situations, I recommend that big guys just skip over the mid-80's, and have some narrow skis for hard snow and some 90+ skis for soft snow.
BTW, if you want to get into more detail on this topic, you *really* need to look back in the archives of Epic. There have been a huge number of discussions of this topic, and some of us who have participated in them in the past really aren't terribly motivated to cover the same material and say the same things over and over again, but are more than willing to build on those discussions.
Tom / PM
PS (in edit) - With respect to your question on length, my experience tells me that you should first be worried about getting the correct width and flex. If you are carving your turns in soft snow, I find that minor changes in length makes surprisingly little difference until you are going Mach Stupid and want the extra length to smooth the ride.