I'd go or the 170 goal, live there a while and see how you feel. If you aren't satisfied, set a new goal.
This issue of "what should my goal be" will be a lifelong challenge on primal, because you'll meet your initial goal relatively quickly. When the problem of "I'm too fat/I don't have enough muscle" is fixed forever, what's your goal THEN? I've been facing that head-on lately.
Zone diet on and off for several years....worked, but too much focus on exact meal composition
Primal since July 2010...skinniest I've ever been and the least stressed about food