Jack,
Retarded ignition timing will make the engine run hot all the time, and once the engine gets to a critical temperature, the water pump will cavitate, making the whole problem cascade. I hope that's your problem.
If it's not, you can add the electric pump as a supplement without gutting your current pump. I would mount either pump in the front compartment initially, but the Aussie pump fits great at the engine. With a front pump, you can use the fan thermoswitch in the radiator to control the electric pump (to full speed) and maybe run the pump at half-speed at lower temperatures, or just use the thermostat-control that is optional with the Aussie pump.
Confused?
