The thermostat really has only two jobs. It remains closed for quick warmup and it helps regulate coolant temp.
I assume since this is a Gen 3 hemi swap that it is computer controlled. As such, you don't need to monkey with trying to run it cooler than the factory intended. That will booger with the whole ball of wax and it'll never run right. That computer is programmed to run that engine best in a range of temperature within itself. That's why they run higher opening temp thermostats. Running them cooler will result in driveability issues at the very least.
