Okuma lathe retrofit servo help

Hi. We operate a lathe with two turrets similar to your setup. Basically, we use the rear turret with negative x values. The tool orientation is still as per the manual. G2,G3,G41/42 is opposite to the normal setup on the positive side of the center line. 

Alternatively, you can issue a G10L2P1R180 before using the rear tool. This works as well. I've tested this, but not used it much.

There is also a cam postprocessor for fusion 360 that allows use of the back tool successfully.

remapping the g10 command is a nice way to go.
I haven't tested this technique on my lathe but played with a simulator.
It doesn't reverse the spindle but you could probably add that too.