It might be an idea to contact someone like
Master Power Brakes and enquire about this.
Most of the ones I've seen are in the smaller F*rd and Chevy patterns.
I would doubt your local FLAPS would carry something like them.
It may also not be possible to re-drill the rotors due to their construction.
Maybe that's why they only seem to be available in the smaller sizes.
Hopefully someone will prove me wrong!