What bow are you shooting?

Are you shooting with a release?

If you're shooting a modern compound bow, especially an aggressive cam, high speed model, then most of the charts aren't accurate for your bow, or will have guidance which says, "if shooting faster than 280fps, move over one and down one on the chart" which typically bumps you up a spine stiffness in most brand. If you're shooting with a release, there is virtually no negative consequence from shooting arrows "too stiff."

So IF you are shooting a high speed bow, OR you are shooting a release, then you'll likely either be better off, or not affected at all to increase you spine stiffness. I would personally shoot the stiffer shafts (the 65/80).