bolt spacing doesn't matter as much as how far out the caliper is mounted. Because larger rotors require a caliper to be mounted farther away from the hub center
For example, the four different S13 calipers all use the same bolt spacing. But the adapters are different. If you buy an adapter but then use a slightly different caliper it will either hit the rotor (spaced to far in) or only partially fit over the rotor (spaced too far out)
I really doubt you will find a pre-made adapter for your combo. Guys who used the 257mm S13 vented disc made their own adapter
Adapters are easy to make, just drill four holes in a 5mm piece of steel. Here's a fancy one with central lightening hole and rounded edges. But sometimes a simple rectangular piece of steel works just fine
This one is designed for B110/B210 strut (84mm bolt spacing), but it only works with a certain caliper/rotor combo
Other combo needs a dogbone-shaped adapter similar to this
the B210 120Y factory caliper bracket for PBR caliper is similar
Designing the adapter takes some trial-and-error to get the spacing correct. Some use plywood for the first few tries, then when it finally is spaced correctly, make a steel version