CNC Lathe cutting a left hand thread

I want to cut an external 5/8" left hand thread.
My lathe is a converted manual machine, which means that it was designed to have downward pressure on the toolpost situated on the operators side of the Z axis.
I don't see cutting from left to right as a possibility because the tool needs some distance to accelerate before reaching constant threading feed.
To cut from right to left the spindle needs to turn clockwise, (opposite normal), and the cutter needs to be upside down, or mounted behind the spindle, (Z axis). Neither of those options put down pressure on the front end of the carriage. But does it matter.
What is the best way to do this operation?
Ozzie

with linuxcnc you can add a tapered entry move that is synced..

The screenshot shows the path cutting from left to right with the spindle spinning m3.

can you do that maybe? that would allow you to have enough room to get up to speed?

sam