Max backspacing for 18" wheels in the front?

http://www.forabodiesonly.com/mopar/showthread.php?t=58491

Lots of info on backspacing and combos there...

From what I've read, that's too much backspacing for the front. Plus it's a super wide rim.. I think you will be smashed into your outer tie rod end with that backspacing and width. Most of the Mustang rims being run are 5.6-6" BS and are 7 or 8 inches wide for the front.

It also sounds like you will need the offset kit for the rear, too.

Here are some SVT-esque rims that are a smidge more narrow and have a better BS... not sure if you're dead set on the EXACT SVT style..

http://www.americanmuscle.com/frchwh1.html

Hope this helped.