Sprint Car Water Pump Choice: Mopar or FlowKooler

I'm having trouble deciding between the FlowKooler 1700 pump for the small block Mopar or the Mopar Performance P4876548. Is the heater inlet and outlet going to have a negative effect on cooling? Is the Mopar pump worth an extra $100? What do you guys think? They both have cnc impellers and are designed for high flow.