672 Polapan 400 3.25 x 4.25" Instant Black & White Print Pack Film (ISO-400)

I am curious about this polaroid film. If I am shooting medium format tri-x 400 rated at 250, and I also have a polaroid back with Polapan 400 and I shoot that at 250 as well, will the results with the polapan be similar to what I could get with the tri-x @ 250? I know they are different films with different properties, but would it be a close enough to test exposure and maybe proof some filtering, etc? This may be something I have to try myself. I am thinking the polapan would just come out too dark, or do I let it develop longer in it's pack to compensate?