There apears to be conflicting and confusing posts.
35mm forks: If you are retaining the original Rotor then there is no difference relating to the position of the rotor and fork mounts for a caliper, between a Spoke wheel or Mag wheel.
Remember the same Yamaha caliper fits the Spoke and mag wheel without and modifications or difference
If you are changing the rotor then depending on the rotor profile, Spacers may/will be required, the same spacer would work on the same Bremco and aftermarket rotor set up. using either a Spoke wheel and Mag wheel,
RG's method appears to be the simplest if making the bracket yourself. This bracket should work for a 25mm forked Spoke wheel retaining the original Rotor