Very cool! I like love that color on the 05-09 Mustangs. What are your plans for that beast besides wheels?
Your wheels will fit on the S197 GT you're looking at for sure. However, the rear offset on a 05-09 Mustang is +45 compared to the +30 offset of a New Edge. If you run a spacer of some sort you shouldn't have any offset issues.
People have ran S197 Wheels on New Edges and vise versa before in the past so I don't see a problem with it. You'll just have to test fit them and see how they look.
I hope this helps!