The line going from the carb to the rocker cover should have a PCV valve in the rocker end. That's crankcase ventilation, not directly connected with the fuel system.
If you're sticking with the Chevy, and your tank leaks anyhow, you might want to drop and replace the tank and install a sending unit with a single line.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
