Twin IDF 44 fuel lines

I have twin IDF 44's on a Ford manifold and an original mechanical fuel pump on my Escort MK2 RS2000 and need some guidance on what fuel lines from the fuel tank I need to run (standard under boot tank and sender unit). Do I need to run both the fuel feed line as well as the return line? If so where would I connect up the return line at the carby end??
 
Any help much appreciated.

Thanks Drew. I've got a 1600 sender unit and will give it a go.
 
Cheers,