go to a club fitter in your area and get fitted if it's a concern to you. Use whatever shafts/shaft flex you feel comfortable with. I personally no longer believe you must have special clubs for any SA method. IDK much about what the Graves Bro.'s are doing, but with NG they said you need to extend the clubs 4", use bigger grips, and a more upright lie angle. That's all good and fine if that's your preference, but remember something. Moe also used golf clubs so heavy (E3) that most would not be able to swing them. So if we're going to follow Moe in all other area's, it only makes sense to follow him in that one, too. Yet, if NG or anyone else made clubs to that specification they would never be sold.
Something else to think about:
+ While it's true Moe extended his clubs about 4", it's also true he gripped down 4"! In other words, if he had never extended his clubs and just gripped the club where you're supposed to grip it, he would have been gripping at the same length as he was when he extended them 4" and gripped down 4".
I think there is a lot of confusion in the SA community, which is why I no longer associate myself as a SA golfer unless someone actually asks me. In this community, many have yet to differentiate between preference and fact. Another example: Must you use a 10-finger grip or can you use a SA grip with an overlapping grip, for example? Answer, YES! It's factually true, IMO, that gripping the club in the palms of your hands will produce better results. But it's preference to use a 10-finger grip like Moe did later in his life. If you use Graves, I'm sure you're aware he used an overlapping grip most of his life. Then he changed and spoke like his 10-finger grip was fact, when in-fact the only thing it was, was simply preference.
If you can get through that confusion, of separating facts from personal preferences, you'll do well with any SA method you chose.