The Granada had a conventional upper/lower control arm where as the Fox body cars had a strut type suspension. So, in that regard they are distinctly different. That said, the issue with disc conversions (or upgrades) are hubs/rotors that fit the Pinto spindle, a place to bolt the caliper and the alignment of the rotor such that the caliper fits around the rotor. What type of suspension they came off of is basically irrelevant as long as they meet the stated criteria.
I believe (but may need to be corrected) that in the Granada to Mustang/Falcon conversion the spindle, caliper and rotor are compatible with the Mustang/Falcon ball joints and A-Arm configuration. Thus, the conversion is rather straightforwar d and simple. On the Fox body cars the spindle is attached to the strut. So, there is no opportunity to blend it with the Pinto suspension.