WTB brake caliper brackets for 12" rotors?

I'm in the midst of putting 18" Mustang wheels on my Duster and I figured out I'm going to need to run 1/2" wheel spacers up front to clear the hubs. For that I'm also going to need longer wheel studs so I figured I might as well use the opportunity to upgrade my front rotors from 11" to 12" (Cordoba rotors) since I'd need to remove the rotors and press in new studs anyway. I don't know where to find the correct caliper brackets though to work with the bigger rotors, anyone know where to look? Junkyard is pretty much out of the question, there is one yard that supposedly has old stuff (pre-1990s) but I've never been there and it's most likely closed due to COVID-19.

I'm also curious what kind of performance increase this will give, if anyone has done this upgrade before? I learned recently that late-model (2014+) Mustang brakes can be swapped on our cars but I'm not sure if I'm ready to make that plunge yet.

EDIT: Just to clarify my car does have the 1973-up front disc setup