It seems the only currently listed loads for the 256Win Mag are on Hodgdon's data web site. They list loads using H4198 and H110.
I don't think Accurate ever listed No. 9 as a powder for the 256Win, and they don't list any loads for the 256Win in their new download PDF load data. In Accurate's Number 2 load book, they do list loads using AA1680 and AA2015 for a 65gr FNGC, the Hrndy 60gr FN, and for Speers's 75gr FN bullets.
I have been using AA1680 in my Encore 256Win. I have not chrony'd my best load yet, but I am getting a 1" group at 100yds with Hornady's 75gr HP bullet, on a day with no wind.......
If you send an email to Accurate Arms attn: ballistician with your question re: No. 9, you may get a response with a number of loads from Accurate, and they may even have a recommendation using No. 9
O/W I would recommend you follow Hodgdon's loads for H4198