The Dunlop Jimi Hendrix Fuzz Face sure looks like the original. Two knobs and a switch. All battery powered with no DC power jack. Mostly authentic. However, the new version uses NPN silicon transistors.
That's good news. The NPN transistors are the same polarity as the transistors as most pedals out there. A DC power jack can be installed and it will have the same polarity as your other pedals. The Fuzz Face can be powered by a brick or 1-spot without any problems.
Adding the DC jack is easy. Drill a hole, install the jack, and do some minor rewiring. Another option is to install a LED indicator.
Adding the LED indicator usually means replacing the DPDT switch in the Fuzz Face with a 3PDT switch commonly used in boutique and DIY pedals.
Below shows where a jack and LED grommet have been installed in a fuzz face. The INPUT and OUTPUT jacks have been removed to make a little room to work in.
Below shows the all the new wiring in place. The connections from the DPDT switch were migrated to the top two rows of the 3PDT switch. The last row provides a connection between ground and the LED when the pedal is engaged. A 4.7k resistor was connected in series between the DC jack and the LED.
Here's the modified pedal. A nice bright blue was selected for the LED color.