Changing the bolt pattern requires swapping in mustang front hubs, and having the rear hubs front rotors and rear rotors re-drilled in the mustang pattern. I
f you have a shop re-drill the rear hubs and press in new studs, re-drill the rotors and find wrecking yard front hubs, you are looking at about 3-500 dollars plus having your car down while it's apart.
BTW, I did the swap, but I was doing a mess of mods anyway, so it was just one more thing on the list.