One of those... possibly A... should have been connected to the air intake tube for the choke heater, which I just now noticed you are not using. I seem to recall on both my L78 and W72 that the *other* loose vacuum hose would plug somewhere in the front of the carb to a small port. It's still vivid in my mind because that hose was somewhat brittle on my W72 and the end actually broke off at the carb as I went to pull on it, so I cut a fresh length and replaced the whole line.
(I'm thinking it's the port above the driver's side idle mixture screw but I can't really recall for sure. Is that a factory Qjet, by the way? I ask because I just noticed the edelbrock logo on the manifold, so....)