Thanks martymexico,
 
The 64mm hole in the center of the CAD adapter bracket in this thread is too small to pass over the end of the diff housing flange at the end of the diff the way you describe it. I could cut a section out of the CAD adapter bracket in order to mount it inward of the flange so it's on the diff center side as you describe but the CAD adapter bracket design as it exist in the file to me indicates that it exists as drawn so I can't see it being installed on the diff center side of the flange.
 
Hopefully NQRS himself or someone who has used a similar adapter bracket will comment as the only way I can see it fitting is as I described 2 posts ago.
 
Thanks for the info anyway.
 
Chuff

You could send NQRS a pm ?
Was thinking that the focus rotor is quite shallow and adding that to the rear axle stud flange sits out quite far compared to modern cars. So maybe the caliper bracket could sit over the bearing plate. I'm only assuming this if you've got the calipers and rotors you could simply lock the caliper on the rotor with vice grips and set the rotor over the hub ( once the backing plate ) is removed. Simply run a straight edge along the caliper mount bolts and see where the bracket will be best mounted. If nothing lines up as you'd like, you can use washers or thicker standoffs to get it spot on..
Fun fact, focus rear calipers are identical to the old Sierra calipers apparently...

I'm thinking that my safest option is that it's time to visit Pick-A-Part, buy the Focus bits and pieces and dummy it up and then take measurements in the real world.
 
I'd hate to spend $2,500+ on rims and tyres based on a theoretical guess and be out by a millimeter or three.
 
Off to Pick-A-Part tomorrow. 
 
Chuff