Using mustang rotors for 4.5" bc

So I'm pretty new here and I know this is kind if old but why doesn't anyone use these? I found out in my car I have this as part of a kit from this place they sell along with the KH calipers. They're already machined and come standard slotted or drilled. They work perfect on my car. Maybe I'm missing something. This is just the slotted one but if you look at the application chart it's for our cars.