Wow! The vacuum lines for the 400 are quite different than the 350! Does your manual have a diagram for the 350 with cal emission?
I think you are on to something tho with the diverter valve controlling when the air is introduced into the manifolds.
While we wait for the photos of the stickers, would you be willing to share some pics of how your vacuum lines are setup? I’m going in blind and would love to have an idea of how this thing should be setup. I’m especially interested in how the smog pump valve is connected to vacuum. Thanks!
Did you ever find pics of the labels you needed? I have a 76 Big-10 that has HD California emissions so I’m looking for the same stickers you are. I have found them on this forum yet so let me know if you find what you need!