If you want to calibrate your colour head so that the exposure time will be constant as you change contrast, you can use several methods. I used Paul Butzi's method which was published in Photo Techniques in 1998. It is quite tedious, in my opinion - you need to do it for each paper you use, or at least you need to test with each paper you use - but it does allow you to change contrast without having to adjust exposure.
I first did this several years ago with Ilford MGIV and thought that I had made a mistake because I couldn't get higher than about grade 3.5. However, as I later discovered, I can't get any higher with that paper on any enlarger I used. I was so naive at the time that this came as quite a shock! Now I am used to the fact that all papers are different and you really need to explore each one.
Coincidentally, I also used Oriental Seagull for the first time yesterday. I used MG filters because I have not tested the paper yet, but it is remarkably different from Ilford WT. In a side-by-side comparison, it is very yellow-green (developed in Dektol 1:2 for 2 minutes). I am not sure yet if I like that, but I am guessing that this colour cast will disappear somewhat with selenium toning.
Good luck with calibrating the dichroic head, if you decide to go that route. If I can be of help, let me know. I am no expert but I do learn from my own mistakes.