Two things
First, here's a picture from the 1936 SouthBend document How to Cut Screw Threads in the Lathe - Bulletin 36A
View attachment 370581
It does show the follow rest on the right side of the carriage, but the tool is moved over across from it.
Second, from Erich's photo above in post 7:
View attachment 370583
Would this cast support rib (yellow arrow) preclude mounting it on the other side of the carriage?
It's not flat.
.....and is the notch in green a cut-out for working around the follow rest?
or does it have some other function?
-brino