1966 mustang suspension?
As long as they're from a 1965-66 Mustang and you take the entire suspension, steering, and brake system from a v8 car then you're good. That includes the front spindles, brakes, springs, pitman arm, drag link, idler arm, idler arm bracket, tie rods, and tie rod sleeves, complete rear axle(5 lug on the v8 cars), leaf springs, all the brake lines, etc.
All of these parts are incompatible so complete replacement is necessary.
1967 up has some different parts(including the spindles and tie rods) so I'd stick with the 1965/66 stuff.