I think (yes I know it will give me a headache) it should draw vacuum from the lower intake or at least in the lower part of the upper intake where the rest of the vacuum lines live, my thinking (headache is getting worse) not to give fumes a chance to build up in case the engine coughed into the intake.
but I have been wrong before
Ok, most of the time
Ok, nearly always
Your intake should have the connection under it, you might be able to get at it without taking the intake off or maybe just jack the motor up to give your hand clearance in the back.