Since you said in preporation for final paint then just painting for a temporary rust prevention is not the plan I take it? If so then what you will need is the smoothest metal you can get before you put any primer on it and that will mean needing to know what it was blasted with and what is it's present condition. Until you know that I wouldn't worry about the type of paint to use. It could be several things.
Remember, you'll never see a body shop take a car directly from the blasting room to the paint room. It must be prepared first unless your looking for a homebrewed paint job that will stick out like a sore thumb. No paint job is ever going to be better than the preparation that was put into it. And it's true of your garage door as well as what's in the garage.
