CR-10 upgrade Dual Z from single stepper

This is my attempt at dual-Z upgrade for CR-10 using a single stepper motor.

It uses a 600mm lead screw kit such as this one:

https://www.ebay.co.uk/itm/3D-Printer-T8-Trapezoidal-Lead-Screw-Rod-W-Nut-Coupling-Shaft-Bearing-Mount-Set/152604546903?hash=item2387f09757:m:mBqqygoYqpae9LmSj9iyFCQ

making use of the pillow block bearings and lead screw nut that are provided in the kit.

Also requires:
2x 20 tooth 8mm hole GT2 drive pullet
1x 20 tooth 8mm hold GT2 smooth idler
1x 760mm GT2