The grade numbers of different manufacturers do not necessarily agree with each other. If you want to try graded papers, then try the lowest available grade for each of the available papers - one of them might work for you. If none of them is soft enough with your current paper developer, you can try a Selectol Soft-type developer such as Formulary TD-31 or Freestyle LegacyPro Select Soft.
Originally Posted by Arcturus
Again, the grade numbers are arbitrary and don't mean much, other than that for a given combination of light source, paper and developer, higher numbers will mean greater contrast. The grade numbers are not standardized or rigorously calibrated. If you select products based only on the stated contrast grade you may miss out on combinations that would work well for you.