I would go to a top sailmaker. I would probably use one of the f18 sail designs and make the front of the boat fit. The big advantage is, existing F18 sail designs have been tested. I have had 5 custom sail rigs built. 1 out of the 5 was SURPRISE, you didn't think of that

Based on 6.0 experience, getting rid of the overlapping jib will help upwind performance, a lot. Adding the sq top main will move the center of force aft. It will probably load up the rudders and you will have to experiment with mast rake


I would keep the foil. The 5.5 bows are pretty flexible.