I am going to annoy some people with with overlay, but I think the existing Mustang canopy is just fine when you re-scale the template, and use the new template which has been discussed.
Overlay-Ford-Mustang_zps568802bb.jpg Photo by kach22i | Photobucket
I am against grille blocks, not in love with belly pans, so that leaves front chin spoilers and wheel covers.
I would not molest your Mustang too much, you may hate yourself later for it if you do.
Maybe the right combination of grille block with a type of chin spoiler which deflects air up into the radiator (like a race car) will work.
http://s184.photobucket.com/user/kac...%20Ends?page=1
I'm pretty sure #3 is not going to do a thing with respect to this car. I just wanted to see what it would look like.