A point to ponder, your average Okinawan is around 5’4” and they use “raku shaku bo” standard six foot bo. When training with various Okinawan instructors in Matayoshi kobudo I have been instructed to grip the bo with my hands in such a way as to separate the bo into equal thirds. In the next breath I’m told to keep the bo closer to my body while keeping my forward hand extended and my rear hand at my belt. I could get close to what they wanted (I’m around 5’8”) a student of mine at 6’ could not come close to making them happy.
My experience is that the longer you are the longer your bo needs to be. However many tournaments will require that you use “raku shaku bo” standard six foot bo no mater how tall you are.
Good luck.