273 4bbl, carb replacement?

As long as it's not blowing coolant out I wouldn't be too concerned. You may need a new radiator cap. It could be loosing pressure thus lowering the boiling point. What is your timing set at. 273's like 10-15° initial. Not enough advance can aggrevate overheating. Too much can cause detonation. That carb should be perfect and it might need to be freshened up but I doubt it's the cause of your heating issue. A good cooling system flush may help.