are your SU's flat top or round top?, i have no pipe between the two carbs and think it may be for emmisions on a flat top SU???

i ran the tappit cover breather and crank breather to a plastic bottle (fabric softner container) with a filter (kitchen scourer) cable tied to the top, been checked by cops and scrutineers for rallying and passed both everytime

and the only male connections i can think of are for the fuel and just link to the fuel bowl, but then again maybe its for the vacuum advance, cant remeber what that looks like

ill get pics of all angles anyway and have a second look where you are talking about