Well then just build your own narrow 6 bolt hub.. Can be made in under 10hrs on a manual lathe..
I think the narrower width where spoke heads sit, may be less ridgid than a wider hub..
70,s Ysmaha mags..i squeezed a 6 piston caliper into a Ceriani GP fork using that wheel..320? Rotor I think.. Will try to post a pic later.