If you've not yet got an extra relay, how are you connected the v3 relay?
Are you connecting it so the spindle only works in one direction (i.e. only applying power to one side of the contactor) when active, or as a changeover so there's always power to one of the contactor coils?
For now, i just want it going in reverse..

If you're going for the one direction, then you need to assign the Relay output # to whatever pin you have the v3 dir terminal connected to, then set the dir pin in Motor Outputs to something that's not being used.
the DIR on spindle V3 board is on pin 8, so i need to set the Spindle Dir pin to 8? and for the motor output it needs to be something like 14 (not being used/connected)