Between 45 min and an hour and a half.............
I forget if 79 is like this, but the 84 (Bonneville) you need to drop the steering column to get 1 bolt with a socket. I've collected 3 in the past month.
The 79 will have 2 special 8mm sholder screws on the top side of the dash. I'd keep these since they won't overtighten and ruin your dash when you reinstall