hmmm, at 5-feet-nothing, that's pretty petite. And the way bra cup sizes measure, I find that the smaller the person, the more cup size they can get out of a specific volume of breast flesh. For example, I am a slightly loose 40-42 C cup, which while about 3" of projection from the chest wall measurement, is easily as much breast flesh (but more flattened out/wider) as a 34D.
Plus, while a cup of fluid is technically like 246cc's, it seems that when it comes to bra cup sizes, about 200cc's is a cup size for most people (depending on profile, placement, and the person's overall body size). So 750-1000cc... would probably be 4-5 cup sizes, putting her at like a G cup.
Not sure whether even the more ambitious docs would put 1000cc into a 5ft tall girl on the first go... you'd have to check with them.
On a personal note, my favorite big breast models (read that as "girls I envy") tend to be smaller framed girls who are around the G cup range (denise milani G, jordan carver H, alice goodwin G, etc.) I'm sure your girlfriend will turn out spectacular
