Increasing Z axis travel

To gain more Z travel I have raised the frame up from the spoil board by using 60mm extrusion, the machine is now all assembled and ready to go, objective is 3D milling to make large Extruded Polystyrene parts for mould plugs so the load on the frame and the spindle is minimal with the taller setup, the question is what do I need to do the extend the Z travel limit to accommodate the greater mechanical travel;, is is a simple config change somewhere or something more complex