First post, been learning a lot lurking!
At the moment I'm working on an eBay-sourced frankenbass. 30.5" scale with a chinese (Stagg) neck on an old Epiphone ET-280 body. I'm planning on a GFS MM pickup in the bridge, but neckwise, I was thinking a four-conductor mudbucker, say a DiMarzio Model One.
First Q is maths; should I measure the MM pickup placement from the bridge as if this were a proper Musicman, or should I adjust the placement for scale, which would be closer to the bridge but the same relative distance between bridge and nut?
Secondly... anybody got a clue how I can do this with the wiring using mini toggle switches (I'm not a fan of push-pull... why spend all that effort modding the bass without showing it off

)?
I can read a wiring diagram... but despite my best efforts am unable to construct one.
Would appreciate any help from people who know more about such things than I!