Proportioning Valve

Got a question for yall. I'm almost finished installing disk brakes on my 71 dart. Car was originally manual drums all the way around and now has the 73 and up disks and I added a booster too. The question is, does the prop valve need to be changed to match the disk brakes? I bought the one that came with the master and booster and went to install it this weekend and found that it looked exactly like the one that is already on the car. Are they different internally or are they the same valve. It looks like kind of a pain in the *** and I dont want to change it if I dont have to. Thanks, Mike