i assume you don't plan on riding too much park with them, so i wouldn't go anywhere in front of the "freeride" position. i have the 180 MSP mounted 1cm ahead of freeride, and they're good for park but nose dive in pow. i've heard from a couple people who ride the 187 that like 1cm-1.5cm back from freeride is the way to go if you're using them mainly as a non-park ski. how big are you?
-Strode