Hmm, I should have had the hole in the spring, but not in the liners. If that isn't the case, let me know and I'll correct the drawing.
I do as you plan to, and drill the holes first. However, if you grind a little short of the lines (leave excess material), and adjust in the following order, you'll find that the hole placement isn't beyond what is easily achieved with a drill press. (That's all I use)
Grind the tip of the spring until you get the tip of the blade where you want it with the blade open
Adjust the top of the tang to get the open spring height