Ace your wasting your breath trying to say it's comparable to a GP to a GA. The two share nothing not even the floor pan. By the way the GT-H is only availble to Hertz. And yes I do call dropping in a 5.4 over a 4.6 as a modification.

Look.
If you were to order a Shelby GT500 this is what happens. Ford builds a GT puts it on a trailer ships it to Shelby who then rips out what it doesn't want and installs the parts it does want. Then ships it to you as a Shelby.

Ahhh what did I find
shelby calling the KR a mustang?

"About Shelby Automobiles, Inc.
Founded by legend Carroll Shelby, Shelby Automobiles, Inc., manufactures and markets performance vehicles and related products. The company manufactures authentic continuation Cobras, including the 427 S/C, 289 FIA and 289 street car component vehicles. In 2007, the company partnered with Ford Motor Company to launch the new Shelby GT, which is based on the Mustang. For more information about Shelby Automobiles and to see the build of a 2008 Ford Shelby GT500KR, visit www.shelbyautos.com."