car sat 4 years. purging old gas?

greetings.

just got a 70 280 sel home that has sat four years with about a 1/4 tank of gas in it and i was wondering what all i should do to the fuel system before trying to start the car.

i am going to drain the tank and put in fresh gas see if i can figuare how to disconnect the fuel lines at the engine and pump fresh gas thru the lines before the old gas hits the injectors.

that's about all that i can think of. (besides cleaning the tank screen and new fuel filter.

anyone have other advice as to what i should do to the fuel system?

thank you jlwggns