Ok, here's the deal.
###edit: it may be the case that my "310mm" disc isnt a full 310mm, and that's why it leaves 8-9mm untouched instead of 5mm.
It bolts right up, but locates the pads too far out for my 310 mm braking disc. I marked where the pads touch it on the inside and then measured the distance between that and the inner part of the rotor surface. I got ~9mm of untouched disc.
So, I don't know if it will work. Maybe my disc is actually a bit smaller than 310.
Measuring the untouched part of the disc, it "should" be around 5mm if my math is correct.
The speedo pickup hole is in the right spot, but the magnet hits the bracket. It would need an almost flush magnet to work.
The "other route" a homemade radial bracket I made:
Speedo magnet interference on my Braking 310mm:
My disc:
Bracket mounted up:
And with pads installed:
I forgot to take a pic from the outside, and had already bolted my other brake up before I realized.
Anyway, I think it will work with a 320mm disc, but just that it may leave a few mm of disc on the inside untouched..