What wheels on your 8.8?

I have a '73 Dart and a rear end out of a 1998 mustang that I believe is 61" if I remember right or just short of. either way to the outside of the fender I have 4.5 to the flange.. I really wanted to get away with not having to shorten the axle I bought 245/60 r15s to put all the way around and was told by my local tire shop a 4.5" backspace would fit but I'm doubting that. I plan on rolling the fenders and i already have us car tools leaf relocation kit in it. I wanted to go with vintiques. I found their 38 series has 5" backspacing. any help would be awesome20200104_201134.jpg 20200109_110021.jpg