I do not think you have clearance between the top of the deck and the bottom of your tractor to get an additional 2 inches ...
The only way you could gain those 2 inches is to raise the tractor 2 inches...
Easiest way is larger tires wheels. You will have to go with a tire size with the first number increased by 4. That will net you a 2 inch increase in operating height.
You will have to check that your wheel wells will take that large of a tire, It appears there is a lot of room to up size.
Your lowest mowing setting will then be 3 inches instead of 1 inch... and your top height will be 6 instead of 4 inches.
That will make for a very different looking lawn tractor. If you do it POST some pictures, it will look good :thumbsup:, I think most all mowers look like they have too small tire wheel assemblies stock. KennyV