Using KOPS for set-back is at best a starting point, but it's fraught with confusion about which part of the knee to measure against, and depends a lot on your particular leg bone lengths.

I've had better luck with the "balance" method mentioned here and on various bikes fitting web sites. Basically start with the saddle in the middle of rails or with KOPS if you prefer. From there I attempt to get to the point where I can "just about" lift my hands from the hoods while pedalling moderately hard, without tipping forward and sliding forward to the tip of the saddle. Move the saddle back until you have almost no weight on your hands at this level of effort. There should still be some weight of course, to provide control on the bars, but I couldn't tell you how much weight this actually is. An alternative to the hoods, is to try on the tops, but in this case you have zero weight on your hands and be able to cycle with just the finger tips on the hoods.

Another important aspect of comfort is wrist angle and choosing the correct weight bearing portion of your hand. It should be at the bottom of the hand near the wrist, in the same spot that supports your weight when doing a push up. Don't support your body weight with the web of your hand, which has lots of nerve endings that can lead to numb hands. Avoid "ulnar deviation", which is twisting your hands downward out of alignment with your wrists.