Stop in for a cup of coffee

So you want to switch fuel pumps?
heres the situation. the 78 w200 I have only has a 20 gallon tank. I have room on the other side of the frame for a 2nd 20 gallon tank, which I also happen to have. the thing sucks gas so badly, I can go about 80 miles on 20 gallons. so I want to add use this 2nd tank, giving me 160 mile range if that makes sense. I've also kicked this idea around for the dart as well since I want to take it on long cruises.