I bought the X-20 tours about a month ago, Project X 6.0, plus 1", 2 degree upright, as a replacement for x-16's which were super in the 3, 4, 5 iron and clunky heavy in the 8-PW.
If you go to the precision website, they list the 5.0 shafts as regular, 5.5 as stiff, and 6.0 as stiffer. The 6.5 is X-stiff. Based on your yardages, I suggest either the 5.5's or 6.0. The 5.5's are lighter and have a lower bend point which will give up higher ball flight. The 6.0's will give more control, lower ball flight, and perhaps less distance.
I've only gotten out twice (also Northeast) with mixed results. Love them for chipping and partial shots, don't have the distances figured out yet. First time out I was short and right, second time out long and left. Must be the indian, not the arrow.