Replacement turned out to be dead.
So I took apart the 12V-to-5V converter and mounted it there instead. I then repinned the 6-pin connectors to forward the correct lines.
I also added some anti-slip tape to the floor pan, some reflectors to the rear fork and brake light, and change the polycarbonate brake light lens to a polethylene one to help diffuse the light better.
I'm currently contemplating whether or not I want to bother going to 72 Volts. It would involve a great deal of rewiring and soldering. I'm no longer really concerned with my range and if I want a slightly higher top speed the easiest way to obtain it would be to replace the motor.
But I'll set that idea aside for a while. At the moment I just want to get the headlight and front body panel done.