If you're referring to the "tree" of vacuum barbs on the intake manifold just below the carb, you don't need any of those with a Weber. You can just cap them, or IMO better yet, use short lengths of vac hose bent in a U shape to connect pairs of them, as hose seems to be more durable than most vacuum caps. If that leaves an odd one remaining, cap that one or use a short length of vac hose plugged with a small bolt.

You might also consider connecting one of those manifold barbs to your distributor vacuum advance, which will reduce combustion temperatures at idle. "Ported" vacuum, which is taken from the carb just above the throttle butterfly, only exists to reduce emissions at idle, with the side-effect of also increasing combustion temps at idle. Before that came into use, all vac advance used "manifold" vacuum like you'd get from that barb tree on the intake manifold.