Jojo, I was able to obtain a USAF KC-135 checklist with reference stating optimum IAS of 250-260knots for a Mirage 2000, when configured with a BDA or MPRS. There isn't a value for CAS for the Mirage 2000, although there is a space for it (notated by a dash). Also, there isn't an optimum altitude, either. For most aircraft with an IAS and CAS value, the CAS is slightly less than the IAS.
However, it is still faster than the KC-130, and I'd love to see the KC-135 fixed.