Thats good news,
Shafts are designed for swing speed if you are fast then you require a stiff slower swing speeds require Regular and uniflex is in between.
Reshafting is very difficult with
callaway as they are "through bore shafts" short for difficult. I would not advise this.
If you are happy to stick with these
clubs then thats personal preference, without knowing your swing speed I can't advise if the shafts are correct, however in between can't be to bad.
Stick with them and practice, they are great
clubs.
Ian.