Having tight kingpins and a properly adjusted steering gear will welp greatly to correct the wander, correct alignment is a must, too. You might even consider seeing if the axle can be shimmed to give a bit more caster for more stability. Radials will also help, but do all 4, not just the fronts. Mismatched tires can cause more problems than they'll cure, especially mixing construction types.
As to the mustang 2 ifs, it really has more to do with getting a car type ride, and perhaps better handling over the stock I beam axle.
