Its powerlifting, I would just try to get stronger. If you are actually fat (at 5'11" and 170 I have no clue how you could be fat, unless you also have next to no muscle) then just try and eat pretty healthy, do more GPP work, ect.
With that height/weight ratio, I would say just add muscle. If you do that right, you may have the same or a little more fat, but end up with a lower bodyfat percentage.
If you want to be good at powerlifting at that height you will need to be considerably heavier..preferably with muscle. Otherwise your leverages will suck.
As far as training, the most important thing at first is perfecting your technique on the power lifts, and using less technical assistance work to start improving strength.
Once you have the technique down, starting strength isn't bad, but depending on your level of development by that time going to WS4SB or something like that wouldn't be a bad move.
Eat, read, lift.