Stainless Steel Brake Crop or SSBC has a kit for converting to a rear disc system. I purchased mine in 89 for about 400 bucks. I bet it is more now. It is on my 1970 Convertiable, 351C.
Pro's. No maintance. I am only now chaning the pads. Never had any pulling of one brake over the other. That is the reason I switched, my old drum brakes got to were they were pulling. Installation was easy. It was all bolt one. Cons. You have to adjust the regulator to get the right front/rear combination of pressure right. You will need an out side observer for that. I can not tell any differnce in the stopping power. I have never been able to get the brakes to "lock up" I have good brakes and the cylinder is correct (I got the one for the kit). However, remember my kit is over 20 years old.
If you think your going to go this route, ask lots of questions.