Sorry Stefano, I didn't realise you were asking a question.
Your compass indicates that the humbucker's screw coil is magnetic south, and the TDPRI link appears to show that the green/red wire pair are connected to that coil. That means the north slug coil is the black/white pair. If your bridge single coil is south polarity as you've stated then you'll need to split to the neck's black/white slug coil to get a hum-cancelling coil pair with the bridge. That means rearranging the mini-switch connections to split to the slug coil. Like this:
It's possible you may still have phase issues, particularly if the two pickups are different brands/manufacturers. It this is the case it will sound thin and nasally in positions 2 and 3, regardless of the mini-switch setting. In that situation swapping the black and green connections on the 4-way switch should solve it. That is, black would go from the mini-switch to the top two connections on the 4-way and the green would go to the lower left connection instead.
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