I had an 2008 isonic 133 and weigh 88Kg. I used it with sails from 7.5-9.0 and they worked great. That size fin sounds perfect for your biggest sail on this board (around the 9m size). Personally I prefered to change down to my Futura when using a 6.7m sail, that said it will take it but only if still flatish conditions prevail.
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