I've disassembled the bass & done a lot of measurements, checking that what I want to do will actually be possible.
Maybe mine was put together on a Friday, or maybe I'm just expecting too much from such a cheap instrument.
Can see why the bridge was not on straight.
Putting a straight edge on these, there's a good 1mm deviation, and they are drilled at various angles into the body too, was definitely done by hand by someone not getting paid enough to care. Going to keep the hole closest to the G, plug the other four and re-drill using a drill press.
Headstock is a similar story, but to be fair the guy had everything stacked against him to get them straight.
The holes bored for the tuner are a shade over 14mm, the body of the tuner 13.5mm, hence the slop back & forth. The nuts were loose out of the box so that didn't help either.
Haven't measured the diameter of the Hipshots yet but I imagine i'll have to do that aluminium tape trick to build up the diameter for a snug fit. The screw holes will be plugged & drilled with everything straight.
And lastly the electronics, thanks to EMG having scale drawings in their instructions I can see that what I want will fit in the cavity with a bit of additional routing, and the existing depth of the cavity is just about right as is.
For anyone who was wondering (as I was) the body is 37.5mm thick including the finish, depth of the cavity is 32mm.
So the body is also just deep enough for a Gotoh battery compartment to be put in the back too, just...