Steve, I think the areas of your Jenny-style tail look good. Also check to make sure the dimensions will be about the same size so it will look good, but the areas are fine. When sizing the tail feathers, you are looking for area X moment. So if the tail is in the same place, the area must be about the same to achieve the same "tail volume." This will guarentee the same control as the original design.

I think you are good, but just to make sure, can you post the length and width of your "new" vertical and horizontal to compare them to the original design?