The JP Superlightwind in it's current foil-ready configuration is a terrific foiling board and plenty big enough even for someone your size. I weigh 102kg and my Tillo shares almost identical dimensions and feels like an aircraft carrier as far as stability goes. If your JP doesn't have the reinforced box you might have someone put in double tracks ahead of the box so you can use the very big low-aspect foils like the i99, but otherwise you already have a nearly ideal ride. It'll probably balance best on a longer fuse than the Slingshot but even the Slingshot will work well if you adapt your technique a little.

Thanks for all the advice. I will look out for an old formula board. My JP superlight wind is not foil ready.