To the best my tired old eyes can tell, my 87 measures somewhere between 56-57 inches to the highest point. Stock suspension, stock wheels, but 245/60 tires.
Put a six foot level on the roof. It is higher in the center then the outside edge. Have 225/60/15 tires all around. The stock GN tires are 215/65/15. Which I think is 1/2" shorter then what I have. I do have new bushings all around, so I think 57" is as closed as you will get to knowing stock brand new car. Mine is 57 1/4" high