What bra size would 850cc's give me and would it look good?

There is really no way to tell if you this will work without an exam.  I will say that 800 cc implants are not typically beneficial due to their size and weight over the long haul.

850cc is a pretty large implant size. Not knowing your breast dimensions but just going on your height/weight, I’d say that would give you a significant increase. However, I can’t say what your cup size would be because bra manufacturers make cup sizes differently. A C cup from one manufacturer could be a D cup from another. That’s why it’s better to go by look rather than cup size. Try a sizer on and then see if you like how you look, instead of checking your bra size.