Should idle at 0 since it is digital. It is one of the options in the Driver Information Center, which is I recall is under the tach (or whichever is on the left side) At WOT is should be around 7 I would say. I was able to get 8-9 in my stock regal, but not that often.
I had a '96 Regal for a while. I liked the car except for one thing...the suspension. Too much "float" for me. It was N/A, though so maybe they have a stiffer one for the supercharged car? If you prefer a stiff suspension, you may want to drive one first to see if you like it.