Hi
Just as a tailpiece to this I tried a little test.
I set up a dti on the cross slide with the probe resting 2mm from the tip of a r h tool.
taking a 2 mm cut with the toolpost mod I got a tool deflection of .0004"
with the topslide refitted I got over 7 times that deflection.
I think it was worth doing.
there is, however, a downside (isn't there always) I now have no fine feed along the lathe, I have not got a handwheel on the leadscrew and even if I had one it would be a pain because there is no quick way to disconnect the leadscrew apart from removing a change wheel.
Ho hum, you win some, you lose some.
Roy