An 89B should be fine with SFX, but having a closer look at the eBay descriptions for your filter and mine, he states two different wavelengths for the supposedly same filter. Mine says transmission starting at 720nm and yours at 700nm. Both are comparable with an 89B and R72 according to him. An R72 is a bit strong for SFX.
You can use this chart for an indication where all the IR filters start transmission.
But this was the point of my original post is that an unbranded filter may not be as accurate as it claims.