Best way to empty old fuel tank of gas?

I just bought a 1974 Dodge Charger ($700) and I am attempting to start the engine. It is a 318 and it hasn't run in 4 years. I tried to pump out the old fuel in the tank with the Harbor Freight hand pump, but the anti-siphon device in the fuel pipe prevented the hose from entering the tank. The tank is on "E" so it's almost empty. I don't want to pull the tank. Any ideas?

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