Fitting a Givi universal plate to an 1100?

Hi All
My Aprillia Leonardo Scooter has a Givi top box on it. It would be handy if I COULD SWAP THIS ONTO MY 1100gs IF i NEEDED TO. (whoops bloody caps lock and fat sossie fingers!). Does anyone know if a Givi universal mounting plate can be fitted onto the standard 1100 rack thats on the bike. Or do I need a special 1100 mounting plate?
Many thanks.

I had one bolted straight to the standard rack for years I then put a 1 inch piece of wood the same shape as the Givi rack to space it upwards, so I could get the lids off my side boxes and open the tool box. The spacer enabled me to mount the box about an inch further forward so putting less strain on the rack.