There are lots of options, but you need to tell us some more about what you want the car to do ... are you planning to autocross or open track the car at all? If you plan to push the car hard in corners you have roll bind issues to deal with, roll center issues, etc.
A really good FAQ about Mustang handling is found at the Griggs website,
http://www.griggsracing.com/suspension.html
--jp