A lot of people have recommended this supplier. www.discbrakeswap.com/

Thats who I am going to use.

 

PO put power booster on my 70 drum non power brakes w/o changing the pedal. I did not realize it until I went to disk and seen the issue with brake pedal. Prior to that they were overly sensitive and could yourself thru windshield with a little force - defintely not safe. Since I was new to classics I thought they was just how power drums worked. Live and learn.

 

Another option is to consider using Cougar power brakes with disk conversion. It is very similar to mustang and can bolt on.
http://www2.cougarpartscatalog.com/podibrcous.html

 

Cougar and Mustang wsere identical in this regard. I still say you should go with the original instinct and do just the power conversion. It's nearly certain that's all you need.