How tall are you? Have you ever gone to a shop with your boat and had a professional measure you for the right paddle with the boat you are using?
My suggestion would be to do this first then you know what paddle length you need before buying. I know they make a lot of longer paddles now but most of them can be a pretty penny and hard to find used. Some shops even have the longer stuff to demo.
"Ipsa scientia potestas est"-Knowledge in itself is power - Sir Francis Bacon
"Beware the lolipop of mediocrity, one lick and you could suck forever" - unknown author