Just a word of warning. I had the exact same brush (cute little sucker) and the knot was in worse shape than yours. I wanted to reknot also. When I started drilling the knot the handle cracked and the top half literally crumbled into four pieces. The handle is two-piece with the bottom part screwing into the top half. The top half is very brittle and what seems to be bakelite.
I've reknotted other brushes so it wasn't just clumsiness on my part. If the Golden Nib has a knot that will fit, you may want to try removing the knot in your brush before ordering.