One approach, assuming you have not cut your threaded rod yet, is to simply extend the dimmensions.
If the machine is already built, you can trim the Y-Axis bottom sheet from 140mm down to 110mm. The mail limit on the Z-Axis is the extruder bumping into the Bars up there. There are a few ways to creatively get those out of the way. That should give you another inch or so that you can move in Z. If you need more space on Z, consider using shorter screws on the print bed.
With either solution you will need to modify your firmware, and print software settings too.
