1970 K20 Fuel System
 

I am currently collecting parts for my 6.7 Cummins swap and wanted to know if I can use the factory fuel tank and location to support this swap? I was thinking the fuel tank may need to be relocated so that it is lower than the fuel rail to allow fuel to flow back? I am still familiarizing myself with high pressure diesel fuel systems so maybe I am wrong about a return line being required. Thank you