spacers

So I finally found an aftermarket or other oe brake caliper that will fit this disc in the front but just need to know if anybody knows of the sizing on the spacers that go between the caliper bracket and the mounting holes on the fork or what I could use instead of spacers like could I use a...

Mikes xs sells carb holder spacers meant to improve low end throttle response and torque, but they are for a 650. Does anyone know if these would be beneficial or applicable to the xs 400? If so I'd love to grab em and see how they do.