My manifold for my Webers does have a plenum chamber on the underside with two threaded pipe plugs in between the carbs. I don't know what brand it is and don't remember seeing a name. I put a 90° fitting in one of those, ran a hose with an inline PCV valve to a tee fitting with hoses going to both valve cover breathers. Works pretty well but I do still get some blow by with some higher RPM spirited driving. Might have something to do with the engine getting close to 90,000 miles
