[Okiesnake]

A lot of performance engines don't have a vacuum advance hose installed and therefore have a tendency to run hot when idling. When stuck in traffic, have you tried revving up the rpm’s a little and see if the temp drops? If it does drop, it is probably not because the water pump is flowing more coolant, it is because of the timing issue. Also if it drops then it is not an airflow issue through the radiator.
To ensure that there is no air trapped in the engine, you can “burp” any air out when adding coolant by loosening either the temp probe or the heater inlet plug (if you don’t have a heater).