Do all A bodies have overheating problems?

Once it's up to temp and the temp is creeping up when the car is stationary, try bringing the rpms up to 1500-1800 and see if the temps come down. I agree with everyone that says it's an air flow issue. There's nothing wrong with your pump or thermostat. What pulley ratio are you running? Under driven water pump pulleys won't spin the fan as fast.