Here are a few pictures of my installation on the Newall Microsyn Scale and reader head for the cross slide on my Hardinge HC Chucker.
I was able to use the dowel pin that held the mechanical stop to attach the scale support bracket. Just made a little adapter bushing and put a slit in it so that it would compress when the bracket nut was tightened.
I also made an aluminum spacer bracket for the Microsyn Scale that has 2 each countersunk holes with 1/4 X 20 SHCS that screw into a .75 X .75 X .25 thick 1/4 X 20 threaded block that fits into TEE SLOT that was originally used for the Manual Stop. You can see the original mechanical TEE SLOT brackets that were OEM on the Hardinge HC Chucker. I also drilled and tapped 2 each 8/32 holes for mounting the Microsyn Scale to the aluminum spacer bracket.
The nice thing about this installation is not one hole had to be drilled into the original casting to accomplish this retrofit.