you do realize that to gain that 1/2 of piston travel that you will need about 3 or 4 inches more pedal travel?????

You might want to do a little more thinking on this as a human cannot move his foot at the speed necessary to use that much pedal

The problem seems to be in your pedal assy---thats what you need to change--not the length of the arc, the diameter of the cylinder, etc