You have to remember that bodybuilding is all "an illusion." What I mean by that is that no one will get onstage and measure your arms, tape your calves, see how tall you are or what you weigh,.. it's all about how you look. That's why conditioning and posing can factor in so much. If you've prepped properly, you've retained almost all (if not all) of your muscle, which means that despite weighing (sometimes much) less, you actually look bigger. If you've learned hot to pose for your individual physique, you'll be able to hide relative weak points and draw attention to strengths. I used to joke about making myself look "better than I actually was."
IMO you need to honestly assess where you are currently as. Are you a real mess compared to a contest level bodybuilder, or are you already one of the leanest guys in your gym? Having some idea of what guys your height look like can be immeasurable. Obviously you may end up looking drastically different than they do, but it can be a starting point.
I'm a little hesitant to throw out my own contest stats, because by my last show, I had 2 pro cards and a pretty decent series of 1st place wins,.. not your average "yeah, I like to compete" gym rat I suppose (in hindsight).
Still, I will say that most guys your height fall in either light, middle or if they're serious monsters (rare), light-heavyweight classes. Lightweight is 150-160 lbs. MIddle is 160-176 lbs. Bear in mind though that every guy you see in those classes has already come down in weight 15-30 lbs from their usual walking around condition. In my current avatar pic, I weighed in at 175.4 lbs, and then probably hit the stage a few lbs heavier (water and carbs). My usual weight was 205, with all abs visable (not deep, but visible enough that my brothers gave me crap for being "too lean" in my off seasons).
Again, I'm not throwing all my stats in here because I don't want you thinking you need to match mine (or anyone else's!) You could come in much lighter than I was and look a lot bigger in the process!