I would say the OP could train the dog to be what he wants if he has the right dog, not just the right people to work with. Protective is a very subjective term. It is on a continuum from an image dog who presents the image of protectiveness, such as being able to turn the dog on to bark at someone, but who, in reality, can easily be run off, to a true man stopper. With the latter, you tend to get traits that are not always so consistent with a friendly dog, such as mistrust/natural suspicion, sharpness, low threshold for defense, etc. An actual guard dog is a dog that has a good deal of aggression and that will bite someone that comes on your property when the handler is not around. That does not necessarily need to be a stable, strong nerved dog. A PP dog is different than a guard dog. Such a dog needs to be social to aloof, but willing to react strongly to a perceived threat. Therefore , a PP dog usually needs to have better nerves than a guard dog, depending on his role. If you are someone who transports cash as part of your business and you want a PP dog, you probably don't need or want a dog that is friendly and social. If your are wanting more of a social family dog that will protect, you probably want a different type of dog.
What are your dog's bloodlines? That will probably tell you with a degree of accuracy if she has the genetics to do what you want with her. Also, everyone wants Rin-Tin-Tin, but not everyone wants to train him. Training a dog to be a PP dog is not for a novice.