1966 Dodge Dart Convertible disc brake conversions

I just found a Plymouth Duster locally it's a 1971 with a V8 it does not have power brakes do you think that one's going to have discs or rotors if it has discs will it have the big bolt pattern or the small one. I hate to keep asking you guys stuff, but there's no way I could answer any other way thank you so much!