First of all, Isonics like more cambered sails.
A 7ish sail with your weight would suit much better on an ISonic 90 or 87.
The IS117 typically prefers more an 8ish sail or even bigger with your weight
What is it that you exactly want to do with the board ? race, freeride, cruise ?
IS87 / IS101 / RRD114 / US147