Have you given consideration to mounting a DRO to the the quill, can be done relatively inexpensively. I had been using the Igaging Absolute, a number of people use a modified caliper or depth gauge. Some people mount it on top, just make sure you can get to the lube holes.
Paint it wipe of excess while wet will fill the lines. That’s what I did to make more visible.
Another idea, Someone milled a small slot, just enough to press in a pocket machinist rule. Turned out nice, and quite readable.