Well since its not just overall ks and its k/9, I think you should look into having 4 RPs and 3 SPs. I've never played in a league like this so I'm probably not the best person to ask, but I think the more relievers you get the better. They can help you in 4 of the 5 categories, and you will still have enough starters to get you wins.
"Oh, that Lankford and McGee, the trio of 'em. They're a one-man wrecking crew."