Dooh. Got it now !!
I had a good chat with Ian at Simmons and he has confirmed exactly what you are saying.
The DBA rotors I am using mount on the back of the Jag hub, so the calipers should have no issue with sticking out proud. I will also measure that tonight.
Simmons have also said that they will give me a dummy wheel to ensure all clearances are spot on.
Cheers