The car is obviously starved for fuel. A plugged fuel line will give these symptoms. Check your fuel lines and your filters. Are you trying to run a 12V pump on six volts electronics. That too would give the same indication as being starved for fuel. With a six volt fuel pump you should turn on the key and hear the pump run until it builds pressure. Once you have determined that the lines are clear and that the pump is operating properly you should have a steady supply of fuel to the carb. You state that you are restoring this car for your boss. With a restoration it is possible that you have all kinds of junk in the fuel tank that will plug the filters. Start at the fuel filler cap and work your way forward from there. Go one item at a time and soon you will have that beauty humming. Good luck.

Art