As Screamer says, avoid cam or freerace sails on that board. Apart from that, you can choose sails depending on the feel you want. At your weight, I don't think you will gain so much by moving to 7.3-7.5 instead of 7.0-7.2, especially not if the sail is heavier with more bottom end. With good technique you might get a bit better mid range, but a bigger sail will bog down the board more and make efficient light wind sailing more difficult (which is what you want the biggest sail for, right?).
But the question in the end is if you just want light wind planing fun (aim for a lighter and "tighter", easily pumpable sail) or more performance oriented locked in sailing (aim for a gruntier, more powerful sail).
I'm not familiar with the Severne sails, but from my brand Hot Sails Maui you can choose either the super fun, light and differernt full dacron "Superfreak" (the only sail with a cult following), the freeride profiled but kind of maneuver cut "Fluid" or the freeride/no cam slalom Speed Demon/XP (one of the few freeride sails that you can get in full xply if you want). Many options and the board can handle them all, the question is what you are after?