cj pony has the spacers and would be able to tell u what will and will not fit i'd think. theyre at
www.cjponyparts.com and in harrisburg pa and their # is 1800-888-6473 if u'r near erie pa theres a place called papony
www.paponyparts.com they have the same parts as cj's and are the same price or a little cheaper and are nice people. also a really knowledgable guy on all ford mustangs made a site
www.dodgestang.com and it has a wheel tire backspacing list on it. newer wheels on the old cars look killer but also really like the look of the thick tire with the 15's or 14's cuz of the way bullitt looked hehe i guess ya can't really go wrong with a mustang eh lol