First consideration is:
Do you still have the V6 16-inch wheels? No easy upgrades fit those.
Next:
Yes, brackets and disks will do it. You don't even need to disconnect the brake lines or bleed the brakes.
And:
Ford calls the brackets something else (anchor plates). They are out there for less than a hundred dollars the pair.
TinyURL.com - shorten that long URL into a Tiny URL
Last:
Each of the GT upgrade kits adds and requires differing components, that will work with some wheels and not others; be sure you have matched what you have with what you want to add.
PS:
Newtakeoff.com has a good reputation and offers the full set for reasonable, sometimes. Just be aware that even the giants make a misstep now and then (bad-guy behavior, you must admit) :
rustydisk - a set on Flickr