Circled in red.
When I pulled one of the vacuum lines off fuel came out of it, making me think it's some sort of fuel pressure regulator --- with a torn diaphragm, perhaps?
The vacuum line I'm still looking for a connection to has a red line on it. It's connected to manifold vacuum on the top, its the 4th of the 4 metal vacuum lines in the "pipe gallery," the one closest to the firewall. I can't figure out where the end at the bottom is supposed to connect.