Need a lot more info here. I'm in the same range and use S because my transition is fast. I would recommend the 30 in 30 that Titleist provides

The type of shaft you use depends on a lot more than swing speed. Sure, we can eliminate shafts based on swing speed (if you're a senior swinging at 70 mph, obviously you won't be able to torque an X shaft effectively, for instance). But the shaft that will optimize your ball flight, and therefore distance, will also be determined by your tempo, your attack angle and your natural trajectory.

If you have a smooth, long tempo you may get more raw distance from an R flex, even at your swing speed, because of the greater flex you'll achieve. If you have a high ball flight, a mid-high kick point will lower your trajectory a bit.

There's a lot to consider. I recommend you get fitted.