Hy RmJr, welcome, I have never seen a conversion kit from single system master to dual circuit master advertised for your size of truck. You have two basic choices a vacuum boosted system or a hydraulically boosted system, the hydraulically boosted system would require the installation of a power steering pump. I recommend using a dual master cylinder which has the same size bore as your original system, certainly not any smaller on the bore. You will probably have to piece together you own kit, just make sure everyone is aware these parts are for a drum/drum system. Good luck and don't be afraid to come back and ask more questions.
