To be safe, you will need to change any part that is made of rubber, or has rubber seals, (master cylinder, calipers/wheel cylinders, rubber hoses) No telling how the rubber brake parts are going to react to the power steering fluid over a long period of time. Brake parts rubber is different than other hydraulic systems that dont see the pressures or heat of an automobile brake system. Also the anit lock brake module will need to be flushed, and all the steel lines will need to be blown out and flushed to remove any residual PS fluid.