Forget the fully battened sail - what you need are really well cut new sails preferably laminate. Then empty out the HUnter - every winter when I race my boat, I'm astounded how much rubbish has accumulated during the season. If you never race the Hunter and never empty it out, then you will find it even worse than I do
In the end you should be able to get it to go through the water almost as fast as the J80 but not in very light winds. Nor will it go in the same direction upwind.