'63 Dart problem

If you rebuild the carburetor without cleaning the source (tank) you're pissin in a fan. These tanks are OLD and sediment and rust have likely built up over time and need to be cleaned out. I recommend removing the tank, taking it to a competent radiator shop and letting them clean it. Remove the carburetor, take it apart and inspect it for dirt and sediment in the float bowl. Remove the fuel filter. Blow out all of the fuel lines with compressed air. Put the clean tank back in. Put a new fuel filter on and clean the carburetor and put a new (not NOS) kit in it. Daytona Carburetor has ethanol friendly kits with good instructions.