The official answer is no, we do not have any shims for the G3 Ion.
I did take the time to size up some of the B&D shims to see if your idea of drilling extra holes would work. It appears that the Radical FT/ST shim could work, but I can't say for how long as it is not intended to be used with that binding. Drilling extra holes in the shim may cause it to crack or fail in some other manner. If you decide to try it, keep in mind that you'll need to replace the screws with longer ones as well.