I did not use the Givi/Kappa kit and I might be off base here, but I think you could use the Givi mount plate to mount a Shad top case. It won't be a direct fit though. You will need to remove the Givi hardware pieces and then drill holes to mount the Shad top case. The Shad case comes with the plastic sub-plate which can easily mount to a flat surface, and also comes with a bag full of various fastening hardware.Will a Shad top case fit on a Givi monokey plate?
The toughest part of mounting the Shad to a flat surface, is determining centerline of the bike, rack, and case. Otherwise, your case will not be all centered and straight and stuff. And if you're carrying a passenger, you also need to determine front/back mounting position too. And be warned- The front/rear mounting location decision can be a very good opportunity for an excellent marital bonding experience.