Start Here with this guide. Just know there are exceptions to every rule. I'm 6'4" with wide shoulders by all accounts a 240cm paddle should be a good fit for me, but I'm a high angled paddler. 230 feels more comfortable as I tend to lean into my stroke a bit. Long and narrow would be for more of a leisurely low angled paddler. Keep in mind the beam width of your kayak too bit mostly get familiar with your specific style of paddling
http://wernerpaddles.com/fit_guide_widget/
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