There used to be charts available online with filter settings for both Kodak and Ilford papers. Frankly, if memory serves, they really weren't too far different until you got into the extreme ends of the filtration spectrum (trying to hit grade 00 or 5+), so I'd start with the Ilford recommendations and if you don't like what you get, tweak. That's one of the great benefits of using a dichro head - you can set in-between grades and aren't locked in to only Grade 3 or 4- if you need 3 1/4, you can get it by adding just a few more CCs of magenta over the Grade 3 recommendation.