So you're modifying your truss rod cover by adding a guitar to it! Great stuff! Is it the hog or the spruce you've got coming?
I've got a bunch of these trc's now, in koa, cocobolo, ebony, and rosewood, switch them round from time to time to change the look. They're so cheap and look far better than the plastic. I think you may need to put one extra small hole in the top of the truss rod cavity about 1.5mm below the original but it's a very small job. There's a few nice mods you can make on the GSm... new tuner buttons; bone or hardwood bridge pins... but by far the most significant I've found is putting in a bone saddle - gives a really stunning shimmer to the sound.