Also, have you disconnected the line at the pump and tried putting a peice of line from the pump directly into a gas can and tried it? A tank full of sludge, as many are after sitting for years, will clog the fuel line. It sounds like you're aware of that but I just thought I'd ask because sometimes it's easy to overlook the obvious. To be honest, in all my years of working on old cars, I've never seen a fuel pump completely fail. I've replaced leaky or noisy pumps but they all pumped and some were very old.
Let us know what you find.
And by the way, you are correct about the vacuum line. The "in" will go the manifold and the "out" will go to the wiper motor (usually connected to a vacuum hose through the firewall).