Welcome space. I'll assume the back of your '02 QS8's have the same brackets(for the t-bar mount) as the new ones so you *might consider removing the clip mounts from the QS8s and fastening a small piece of wood across the back of the speaker, maybe 1 1/2" x 1" x the distance to the outside of the clips. Use the same holes in the QS8s to fasten the strip of wood. The strip of wood will have a hurricane, barbed, or pronged T-nut properly fastened in it's centre of the right size to mount your ceiling bracket to.
