Well that's interesting. My 4160 is relatively new...purchased only about 2 years ago, and it has the two angled barbs like the upper right hand picture above. I can tell you that the bottom barb on mine is full manifold vacuum as that is the port I used for my vacuum gauge when I was getting everything set up. I wouldn't be able to use it for the distributor in my situation as I would have full vacuum advance at idle.
My 4160 is fairly new also, 2 years old max, I think. 3 ports, two full vacuum and one timed spark vacuum source.