I did this some time ago. Cheap drill press. The original stop had simple jam nuts that were a PITA to adjust and a soft plastic (read flexible) bracket holding the stud to the spindle. And the original hole in the casting that formed the stop had a sloping top so the nut slid across it allowing the spindle to travel even further. So much for any accuracy. It was almost impossible to get consistant results for countersinks or trimming the rough edges. Oh, and it was so close to the head that it was impossible to get a finger or wrench between so you were limited to about 1/8 turn each time.
I got the pushbutton nut from McMaster for about $5. I choose the 3/8-16 size so it provides 1/16" per turn. That's a time real saver when drilling to depth. I can easily adjust in 64ths.
I made a new bracket for the spindle from aluminum. I extended it a good distance out from the head to allow good finger clearance. No wrenches needed with this baby as it is self "locking". Well, it has enough friction to stay put and with a flat surface on the stop it has no tendency to rotate. The Bracket has room for additional future accessories (mike stop?). I filed the top of the original stop flat and added a small piece of HRS for the new stop. I made sure it was perpendicular to the spindle axis. The stud was also replaced with a length of 3/8" threaded rod.
It has made all the difference - night and day. Now I can do "precision" work on my $50 drill press.
Make it fit.
You can't win and there is a penalty for trying!