Your grandfather is rolling over in his grave.

I'm in HGK now and I asked Victor Choi, who owns Dragon Culture antiques and has been around the HKG antiques scene for decades, and he didn't know of any local dealers who specialize in old Chinese books.

BTW, he also said old books are very common in China.

Another dealer I asked also couldn't recommend anyone local. He said if you really think it's worth something, contact Christies or Sotheby's. Good luck.