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The golden nib is a US based seller of knots. Virginia Sheng on eBay as well as shavemac out of Germany. If you don't want to risk it, I'd suggest remove the old knot and clean up the brush cavity...

That's a keeper! Nice find. But you need a new knot in that brush to do it proud.
Or a peroxide soak to freshen up the boar if you like the knot as is...
Either way, congrats.