Devin - when you weld that plug in the hoop, drill through the outer tube and pin in both sections. This will insure the plug never pulls apart or twists. Or at least drill through outer tube and into the plug and fill with weld to fuse the two together.
If you need some spacers, drop me Aline and I'll get them turned for you in aluminum. My buddy is doing some for me for another members calipers on his CBR/Hayabusa (I think) mod.
Merry Xmas
Cal