He should try and get to a fitting day and get to try various shafts out till he finds the correct one that suits him

Have him go to a Titleist Thursday fitting for the driver. I did & it was well worth the time.

You'll hear this from other posters as well - the 917s need to be fit to the player. Even with the same head speed, other factors such as transition rate, angle of attack, and swing path will likely result in far different head lofts/shafts as being the best for each player. I doubt that any retailer in the US would have fitted me (low-mid 80's swing speed) for a stiff shaft but Oceanside did. I'm now splitting fairways and 20 yards longer than with the 913/R-Flex I fitted myself.

Why not have him get fitted? Titleist makes it easy with their fitting events and most shops with fit for N/C with a purchase.
Too big a purchase to guess on what would be the best head/shaft combo.

Hi Nathan!
If it's a gift you might give him the gift of a driver-fitting instead :)
Cheers!