Bogart Drag Star on IRS cars I need your help !

I have a dilema : I need to get some Bogart Drag wheels and they told me ( Bogart ) that a 99+ IRS Cobra rear end will not accept 15"X10" Wheels with a 6 1/2" backspacing , they are telling me that it will not clear the brakes so if any of you have this kind of set up or any 15" drag wheels on a IRS car I'd like to know what is your set up !

Thanks !

( Maybe I should have asked on the SVT side but most of you goes back and forth from SVT to 4.6 Tech )