all of the above links, including global west are excelent choices, most mustang specific shops have handling packaged, ive only ever dealt with
www.mustangsplus.com and can only recomend them... but the first, cheapest and best fix is still the shelby upper arm relocation... on a 67/68 you redrill the mounting holes for the UCL one inch down and reinstall, and with the priec of four holed the car will feel radically different... specs (and templates) can be found on the web