Slant 6 intake question

I am building a slant 6 from a 70 Dart that will go into a 68 valiant. As I am looking over the 2 intkaes, the one in the car now and the one that came with the motor I am building, I notice there is an outlet on the old intake that is not on the newer intake. The tubes or vaccum lines seem to go one to the brake booster and the other connects to the carb. Should I use the old intake or just try to remove the plug that is on the newer intake and attach the fitting and then the vaccum lines? Here are pictures of what I am referring to. The first one is the old motor intake with the lines attached. The second picture is the intake from the rebuild motor.