one of the first things i did to my car was a front drum to disc conversion( came w/ new booster,prop. valve, and master cyl as well). replaced all the brake lines, and replaced the rear two wheel cylinders.
the best money i have invested into the car !!! the way i look at it, what good does it do, to put the money into the car to go fast, if you can't stop it. safety first here.
the total cost was under 1200. including the front end allignment you will need, down to the brake fluid.
http://mattsclassicbowties.com/en-us/dept_48.html