This fellow certainly does some beautiful work. You might want to consider making a step chart from 0 to 100% black in 5% increments, then having this fellow print it. Then you can set the tones in PS to match what you want in the image. For example, if you have an area in the image that you want to look like the 55% black area of the step chart, then adjust your image in PS so that the area is 55% black and you will get exactly that tone from the printer. You can do the same thing in RGB values between 0 and 255 if you work in RGB (this is what I do). If you have access to a reflection densitometer you can also make a handy graph of reflection density (zones) vs. % black.