It really comes down to how much do you want to spend?
You see the option for $1000 above. Probably for 1/4 of that, you can get the late Cougar/SVT caliper brackets and two new, larger Cougar/SVT rotors, even with slots or holes or perhaps both.
Or you can pay some more $$$ and go with the Baer system.
Larger rotors may require larger wheels and tires, depending on what you already have, so you might need to figure that into a 13" kit upgrade as well.
FWIW,
TB