I think it would but it might be a little too big. You can always check the dimensions of this product and the dimensions of the GMMK Pro on the Glorious PC Gaming Race official website and match it up, you may need to do some conversions.
It fits my Planck EZ on the bottom great, but it definitely won't cover the number row on the Drop Preonic on the top of the image. It doesn't seem there is an easy answer for Preonic owners
AJGAMERXI originally had keycaps with the legend on them, but once I was back to touch-typing, I moved to the blank keycaps. I still use a 60% for gaming, but I use ortholinears for my everyday typing and work keyboards.