Raising the seat would be easy if the rail bolts were parallel, but they are not. The forward rail bolt is angled which requires the seat to move forward as it moves upward.
A longer bolt and a metal spacer for the forward reattachment is straightforward. However, now the longer bolt at the rear will not line up with the threaded hole on the floor.
It is possible to fabricate a metal contrivance that will accommodate this problem...I did but I prefer not to share the design due to liability.
Good luck....you will figure it out.