Prusa 12 -> Pegasus upgrade --- Z-Axis Coupler

Hi, I am just starting upgrading using the Makerfarm kit and Titan Extruder. Looking at the initial setup it appears that the X-Axis assembly at its lowest position gets very close to the right hand Z-Axis motor shaft. Previously I had been using the Reprap aluminum Z couplers, but it doesn't look as though they will while allowing the X-Axis assembly to go low enough to print.

Has anyone else done this conversion, can the couplers be used or do I have to go back to the plastic tube type?

ex-egll