if your talkin about the newer billet center one's i know you need the highest arch of the spokes to clear the brakes (i think they have 3 or 4 profiles.
backspacing and width id say something close to what the XP draglights on the TR have but maybe move em a skosh closer to the strut for more lip clearance.
i was looking at these but i wasnt sure how wide i could go or what the back spacing was supposed to be i think most of the mustang rims are 4.5" back spacing and those fit on here fine
i believe i used a 4.5" backspacing. had to use spacers and arp wheel studs as well. i had a set of pro star xp's which will fit perfectly with stock studs and the right lug nuts...lemme text the dude that i sold my car to and see if he still kept the wheels.