I need help to set up my Holley carburetor.?

I have a 600 Holley electric choke, its for my 350 im building for my senior project. Its not like any other carb ive seen, It has two inlets for the fuel line. Im not sure which one to use and which one to cap off. I also have two little nipples at the bottom of the carb, I know one is for the hose that goes to the distributor but the other one im clueless. Please help thanks