Originally Posted by DoubleVision
I`m unsure, but I`m thinking this intake wasn`t made for the use of Vacuum brakes otherwise I`d think there would at least be a provision for it. That`s not to say you couldn`t drill and tap your own or have a machine shop do it. Let the carbs sit on the intake and study the design until you see what will be easiest and look neatest. Good Luck.
A much easier method is to add spacer plates under the carbs they are available with the vacuum port and without. This will also improve the low end torque by keeping the fuel cooler and adding velocity to the runner system. They are not cheap but it is much less risky.