You will need the calipers (which come with brackets unless you get them from Auto Zone, Advance, Etc.), rotors, and new lines. Everything will bolt up to your existing hardware.
I am doing this install on mine as soon as my calipers arrive. I also figured I would upgrade to braided brake hose in the front since I had to replace the lines.
scot 94gt is on the money. I did the upgrade 2 weeks ago. The calipers bolt right up as they come with the brackets but the stock gt lines don't fit the cobra calipers. I went with ss braided lines and the pedal feel is much more solid. I got my stuff from stangsuspension.com.