Very tall woman (6'2") and breast augmentations. Need help deciding on a size (Photo)

Patients often think in terms of cup size when considering augmentation. Unfortunately, devices are sized in terms of milliliters (cc) of volume. This can lead to some confusion when sizing. Additionally, it is important to remember that cup size itself is not standardized with variations from one manufacturer to another. Unfortunately, as many women can attest their cup size in an industry leader such as VS is not necessarily transferable to another brand.
Another point which is often under appreciated is that of anatomy and starting point. Any implant will add volume to the volume which is already present. The implant is additive. A particular volume will not necessarily confer the same cup size to different patients (often times it will not even confer the same cup size to different breasts in the same individual...remember they are "sisters" not "twins"). 
A general rule of thumb is that 125cc can represent somewhere between 1/2 to a full cup size increase. Smaller volume differentials (25-50cc) are typically less consequential representing a volume change of less than a shot glass. However, I have found these numbers, at least anecdotally, to be of little help. Patients often present with notions/goals which do not correlate with these sorts of sterile volumetric assessments.
When sizing patients, there are a number of useful tools including:
-3D imaging (has the added benefit of offering a volumetric analysis of the pre-operative breast)
-Breast sizers (rice bags)
-Goal photos
I also recommend that patients commit to a particular look rather than a cup size. Once a patient settles on a look that pleases them the overall cup size increase becomes less relevant.The key to obtaining a natural result is to stay within the parameters defined by your BWD. This will ensure that you avoid the dreaded "fake" look.
With regards to your specific question, it is important to remember that sizing is not merely a question of having the available skin to accommodate the increased volume. You must have the space on your chest to fit the device. Exceeding the BWD will lead to the implant spilling over into the axilla. 600 cc is a large device but it may be reasonable depending on your unique measurements. Taller patients can often tolerate volumes that would be unreasonable in smaller individuals.As always, discuss your concerns with a board certified plastic surgeon (ABPS).

Thank you for the good question.
 As you can imagine, despite your good description of body type and goals, it is not possible to give you precise advice online.
 Having said that, in my practice I have found that taller patients DO end up with larger breast implants (that seem to fit their frames better than smaller breast implants would),  when it comes to achieving a proportionate look.
The best online advice I can give to ladies who are considering breast augmentation surgery is:

1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you're looking for. Ask to see lots of examples of his/her work.

2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals.
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or “D or DD cup” etc means different things to different people and therefore prove unhelpful.
 Also, as you know, cup size varies depending on him who makes the bra; therefore, discussing desired cup size may also be inaccurate.

3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery.
I hope this helps.