I dont know how well flatsawn will work as opposed to quartersawn. in youre making a neck thru, you should have about enough room to turn the neck on its side, should you not? I understand that flatsawn is used and has been used for necks, but for all the time and trouble of building a neck thru, and having a bummed neck sounds pretty disappointing. save the disappointment and use quartersawn. If youre gonna spend the time n money, should do it rite. just my opinion...