So you want to change your M8 threaded rod to a M8 Lead Screw.
The parts to modify would be the nut lock, to take the nut flanged screw nut.
Also with these most are 2mm pitch but have four flutes, so the pitch to use for calculations will be 8mm. Because for every 1 revolution the nut will travel 8mm.
You do not need the spring with this as there is very little back lash with these.