Looks like you've had a pretty amazing transformation james! Congrats! Can you give us an idea as to what your diet and training looks like right now (as needto asked)? Are you following a doctor recommended diet due to your surgery? Are there guidelines you need to follow since the surgery has been fairly recent?
There are ways you can eat to turn your body into a muscle building, fat burning, metabolic furnace...but we want to be sure you are in line with your doctor's orders/recommendations!
As for training, give us an idea of your weekly routine...both weight and cardio or whatever you may do for exercise (biking, hiking, basketball, etc.).
So, you're 5'11" and 179 lbs. @ 17% and sounds like you'd like to be about 185 @ 12%. I think that's very attainable and maintainable for you. You may find it easier to put on even more muscle mass once you get going towards that goal (due to your body type).
There's a lot of people here who can help you out in your journey! Best of luck!