I think it would be a do-it-yourself item. Perhaps adding a flip-up post at the cover screw.
Might be something to do with the direction switch/control.
*Perhaps altering the direction control adjustable stops to have one (or two) with a threaded bump to intersect the control.
It is not needed very often, but I have needed it a few times..I'm trying to remember the parts that I needed that for.
One need would be if you used an end mill, grind the ends fixture. You would need to adjust the going to the center. Often you might make one flute long to center and the others short of center. I haven't done end mills that way because I always have access to a TC grinder.
Another need would be to come to a horizontal diamond radius dresser...to come to the last dress..and then feed in a little more.
A drop-in (long travel) stop is good for the basic under-the-wheel dresser.
A simple drop-in stick is Ok for that..like a cut-off paint stir stick.
I often keep a tab of masking tape to set on my down dial so I remember my last dress number...that way I know how much wheel I lost making the last grind..That makes shooting to closer size easier.
Close holding the stop of long travel makes that more accurate.