If the fuel line is located above the Intake cross over that would be a potential problem area. The closer the line is to the manifold the more suspect IMO. Adding an electric pump out back as a "PUSHER" sometimes helps as it creates a positive pressure in the supply line which raises the boiling point of the fuel. Keep in mind with a mechanical only, it is at atmosphere or a negative pressure which has the opposite effect.
I have in some severe cases fabbed up a piece of aluminum to cover the heat crossover area bolting it in place to create an air space between the manifold & line. The larger the piece the more it will deflect and radiate the heat away. One could also add insulation to the bottom side to block even more of the heat. I also prefer phenolic spacers under the carb.
Some of the BB Corvettes had a shield under the carbs directing the heat away from the carb and fuel bowls.

It is baffling why two cars that appear to be the same will act differently. It also P'sMO that this problem had gone completely away for decades until they started playing with the fuel and more so ethanol.