Connect the MASTER RESET input of my circuit into pin 15 of the SMPC chip on the SATURN. That pin pulses only once when the console is powered on. I suggest you use the Reset button input (Pin 53 of the SMPC chip) as "toogle" for region changing. As you can hold the RESET button while powering on the system, the state of the flip flop will be locked with the state of the reset button at the time of the master reset.
As the majority of discs I play are Japanese, I wired the two output wires in a way the console is Japanese when the system is powered on with the button released. If you hold it and power the system on, it changes to USA.
The second 74LS74 can be omitted if you don't need it (50/60hz toggle)