The heads are SVO C302B so there is no thermostat housing like there is on a 351C. Each head has a -12AN coolant "out" line that connects directly to the swirl tank. BTW, two temp sensors live in this tank and there's also a sight glass, so it's easy to make sure the tank is full. A length of 1.5" tubing leaves the bottom of the swirl tank and runs all the way to a remote, by-pass thermostat at the inlet of the rad. If the thermostat is closed, coolant bypasses the rad and returns to the water pump. In the return line, there is a Stewart electric booster pump, to help the mechanical water pump pull coolant back to the engine. It's main purpose is to eliminate cavitation.
As an aside, the suction is so strong at the inlet to the electric water pump, I use it to pull coolant through the heater core. The inlet fitting is just before the remote thermostat housing, in the opposite coolant line, and the heater control valve is up there too. The heater hoses pass through the bulkhead and connect to the core with two very short hoses. This would be a good strategy for Coyote conversions, to help eliminate a bunch of heater hose related "stuff" from the front of the motor.