Chris, I ran cast iron discs with sintered pads and it wrecked them within 1500 miles. Considered opinion from others seem to be that sintered pads and iron discs are a no go. Certainly my experience has been just that. Further research has indicated that cast iron rotors can be a bit suspect after a time because they can quite litterally explode with pretty dramatic consequences. There could well be some truth in this because Brembo stopped making iron discs about 4 years ago.
Am reliably informed that the new type "cast stainless" are every bit as good and work well with sintered pads. Having just bought a set last night, i let you know the result!