Just go to the link provided in my above post and print out the Progressive instructions. I don't think you can go wrong. What I did was read carefully and highlight the instruction pertaining to my bike. The instructions provide info for GL 1100/1200/1500.
Oil level isthe distancefrom the top of the fork tube to the top of the oil with the fork tube completely collapsed (both tubes pushed together as faras they will go) and the fork spring removed.
If you go on a few trips and decide the ride is too harsh or too soft, apply the fine tuning instructions.
That's what I did on my GL 1500 and GL 1100A, along with, over the past, two other GL 1500s and one GL 1200. From what I read on this Forum, some have used the fine tuning instructions to change the ride feel. I used the basic initial instructions, no fine tuning,and have been satisfied.
Lucky, you may be Ok with your oil level.
The oil level also affects the ride, too high an oil level and the forks will feel too stiff, too low an oil height and the bike will bottom and feel soft or dive.