You’d get 6 strings through the body and 6 strings that top load, both with the kit bridge and the Gotoh one. There isn’t room for all 12 strings to string-through) The kit bridge used to date is dimensionally identical to the Gotoh, but the saddle heights for each string pair are different by 1-1.5mm (they should be the same) and the holes that should allow the bridge to be intonated correctly for R/H use aren’t tapped for the screw, so proper intonation can only be achieved if used on a L/H guitar or you swap out the nut and fit the string pairs the Rickenbacker way with the heavy string at the top (though the string heights will still be different so playing up the neck will be awkward).

The factory isn’t well known for getting its string-through holes lined up very well, so you may feel happier drilling the holes yourself. It’s not too hard to do and you’ve a much better chance of getting your ferrules in a nice straight line.