The biggest problem I had was that the machine I have is one with the
lead screw reverser down just to the left of the leadscrew. It is nice
because the system also acts as a clutch, so you don't have to stop the
lathe to change lead screw directions.

My Sheldon R-15 has that feature, the reverser is on
the output of the QC, but their QC (80 threads, 80 different
feeds) is more complicated than a 5-speed automatic transmission
with overdrive and lock-up torque converter.

Well this probably won't help you with your Atlas, but I think it's
kind of neat anyway:

In the Hendey reverser shown at http://www.lathes.co.uk/hendey/page10.html
the spindle feeds a hollow shaft in to a bevel gear that turns an
idler bevel into another facing the input but turning in the opposite
direction. The output to the QC is picked up by a dog clutch that can
pick up power from either face of the counter-rotating bevel gears.
This is sent out a shaft inside the input shaft, and then down to the
rest of the QC like you'd expect. Simple and slick.

But the part I really like is that dog clutch is controlled by a
handle conveniently located on the apron. It only engages the
leadscrew in one place, so you don't need a threading dial as long as
you keep the half nuts engaged, and there are stops that will pop the
handle out of gear when the carriage hits them...

--Glenn Lyford