Now it's a li'l easy. At least You know that it should not have any diferences in the front end. Much better this way.
Did You asked the previous owner if the MustangII steering tied to the truck's stock front end showed any sings of bump steer?? You should be sure about it. And finally, about the dimensions I cannot help You much, I just do not have this info here, buddy.
But if it's not visually much different than the frond end, no problem. Just to have an idea, measure from the face where the rims lies against, on both ends and see if they are too diferent.
