look up the "slant 6 fuel line mod" to get an idea on what the factory did there, how modern gas doesnt like it, and what people did to remedy that
then consider how to carry it over to your application
IMHO the best thing you can do is install a return style fuel system to keep fuel circulating
(on my duster, i installed a new 3/8 fuel line and kept the old one 5/16 as the return)
since you are wondering where to put the pump, i supposed you are installing an electric one?