I believe the data sheet that comes in most papers lists ISO speeds of the paper with different Ilford Multigrade filters. However, that is for tungsten illumination TMK. The papers might be more sensitive in daylight. So, yes, I would say some tests at first are the way to start.

I would not recommend using a 00 as a matter of course, but using the filter that will best give you what you want for each shot at hand. To pick this, you will need an eye for the luminance range of your composition (or a spot meter), and trial and error.