Somewhere in this forum I seem to recall the following: The spring pads come in 4 flavors; 1-bump to 4-bump with each having 8mm (5/16")thickness differential. Couldn't tell you if the 1-bump pad starts right at 8mm (5/16") or not. I DO know that my "stock-suspension" 1986 2.3-16V has 3-bump pads up front.
I also read (and does your literature say) that the H&R sport springs will provide 1.3" of drop to the vehicle.
Please let us know the outcome as I am planning on performing the EXACT mod you are going to perform. It would be great if you could record the "before" and "after" fender height readings, as well as, which pads you use and tire/wheel details.