you want as much travel of the fork possible without them bottoming out. i can't remember off hand if the 675 will bottom out 1" from the bottom of the fork leg or not. but like i said you want to be able to use all of the available suspension travel without bottoming or topping the fork out. correct rebound and compression setting also go along with getting the sag set. a good suspension tech should be able to get you pretty close, but also inform you if the spring rate is to much or to little for you. to little or to much spring rate will also reflect on how the damping works in the fork. if the spring rate is to little tor to much the damping will not be able to compensate for the ill effects of the spring rate and will not be able to speed up or slow down the rate at which the fork compresses or rebounds from the effects of road surfaces, braking, or accelerating.