If you are in the mood of experimenting, I suggest you try this approach, tested by me; I dare not claim credit ofcoz, its probably been done by tens of thousands people before.
I shoot provia 100 and pull it to asa 50 or sometimes as low as I can go depending on the lights, and I always pull TriX 400 to two or half stop depending on the filter, and develop them as normal, E6 done at fotohub while B&W done at home.
This approach works for me, especially so for the reason that I do not have to incorporate filters compensation since I am shooting on a “pulled film”, its technically overposing film. I just checked with a senior lately, he validated my approach. I can ask again if you have more questions.
Good luck to you. Hope you have fun with this, and hopefully save you a couple of dollars for every stop.
dtoh
dtohphoto