Seniors type shaft for 975F 13.5* Fairway wood.

Hi, I am 72 years young and play off 18, I have a 975F as above & it is fitted with a "Titleist ultralight custom graphite technology

S" shaft, I recently had my club head speed tested by several club sellers & a leading brand rep. it is between 68 & 70mph

I imagine the weight of the shaft is correct for me but I feel the Stiff flex is not suitable, what shaft which is available in Australia would be most suitable?

Regards John Lovell.

p.s I love the club & would prefer having it reshafted to replacing it.