I think 2.5 inches should be plenty doable with the 3 jaw. How long is the stock? The soft jaws are something of a consumable. They are aluminum and just bolt onto the steel base that rides in the scroll. A new set is less than 10 bucks. See
here. However, if the existing soft jaws have room for an outer step, and you don't need too deep of a step, you can just bore out an outer step to the required diameter. Note that doing so requires one preparatory operation, that is to clamp down on a quarter or something thing in the inner step so that the jaws are loaded when performing the boring operation. One other thing, the soft jaws cannot be physically opened far enough to hit the bed. And yes, they can be flipped (remove two mounting cap screws per jaw and reverse). Typically one side is for holding smaller diameter stock while the flipped side is stepped for larger diameter work.