Stock Fuel Pump

Could be a vapor return or could be a vent line for some version of the 'vapor saver' system. Look in the service manual for your year. You can also review the return line and vapor saver info in the TSBs and Master Tech series.

Don't install an electric fuel pump. It's not needed, and doesn't play well with original circuit design. The carburetor bowl simply needs to be full, not pressurized. I've run enough fuel to a carb on v-8 to drive it around using gravity feed from a gas can.