Holley 1850 return line?

No fuel return. Single fuel line hookup.

The vacuum advance connects to a 1/8" nipple on the primary metering block (right side of the carb). PCV should connect to a 3/8" nipple on the carb base. If you're running a thermostatically controlled air cleaner, there should probably be a 1/8" nipple on the carb base, otherwise cap all unused ports.