i did it with my old guitar too. i've repeared a washburn that didn't work for 12 years...i've changed everything inside and put the "demeter fat control".
i've used a switch to be able to choose boost and no boost for the reason that you need a battery for the boost, and in case that battery is dying, you can turn it to standard mode..it is my best constraction till now, not only cause i gave life to a dead guitar, but i made it sound 10 times better.
the most usefull and fast video that helped me was this one
https://www.youtube.com/watch?v=HrynzPs0NmQ