Proportion valve

Can you guys clarify for me. I am also converting a 73 duster drum car to 74 disc, in front. I was under the impression my manual brake 73 duster could use the manual master cyclinder and the original drum upper control arms since they had the big ball joints in 73. I have the proporioning valve from the disc donor car, but not the master cyclinder. What do I need, Walt :scratch: