don't buy a freerace sail.
You're better off getting a used formula rig off a racer. Your weight is fairly extreme and you NEED all the rig stiffness you can get. My heaviest weight I've sailed at was 260lbs and it makes a huge difference even vs. 240lbs.
What's frustrating is actually getting on a plane. When you're this heavy, the drag from the board is huge which makes the sail distort and feel heavy and overpowered even before you're planing.
Consider overfinning the board a bit too. Spend a lot of money on the best boom you can afford because you can't afford the distortion from the boom flexing. Quality racing equipment is your friend because it's designed to be sailed overpowered by heavy dudes.