Well at 178 the recommended line is back 78mm and since you are going to be using them mostly around the mountain and not the park I would probably +2 cm from recommended line or at the recommended line.
The closer you go to the center the more you degrade the all mountain aspect but make it better for park and switch ability.
I KNOW YOUR NEW BUT PLEASE DONT TYPE IN ALL CAPS, IT IS VERY ANNOYING AND MAKES IT SEEM LIKE YOUR TRYING TO COME OFF LIKE YOUR SHOUTING!!!!!1!!!1!1!1!11!1!!1!!ONE.
just saying man, dont mean to come across as a jerk but its not necessary.