From a dialogue with an owner of a 77, originally with Borrani wire wheels:

   On the front-end, the disk brakes are GM with vented rotors and the 
mounting plane is much narrower than the original Studebaker disk rotors.  
This requires an adapter to A) push the wheel outward and B) change the bolt 
pattern to the Ford (5 X 4.5") type for the Borrani hubs to mount onto.   The
adapter bolts to the GM rotor and has 5 lugs to mount the Borrani hub onto.  
The adapters are approximately 1 inch thick.

  The rear had GM drum brakes and between the drum and flange, inside the 
drum, is a spacer to also push the drum outward a bit.