I'm shooting 8x10 Foma 200 in low light conditions outdoors (thick canopy of trees that allows in filtered sunlight), and even with adjustments for reciprocity I'm having a hard time getting the amount of shadow detail I'd like without getting too much exposure in the highlights. Any suggestions for a film that might be more sensitive at the low end of the scale?
I don't think a magic bullet exists for such a difficult lighting situation---it is not a film choice issue IMO. I think it would be problematic for any b&w negative film.
You are describing a high contrast lighting situation with deep forest shade and splashes of sunlight. I think you are going to have to provide enough
"exposure" to register detail in the desired shadow area(s) and then plan
"development" to control the density in the important highlight area(s). This is the classic
"expose for the shadows and develop for the highlight" situation. There might be a contrast ratio of 10,000 to one in such situations and you are going to have to expose and develop the film in such a way to reproduce it (or express it to satisfy your vision of it) within the limitations of the paper, which, you can be assured, is nowhere near 10K to 1.
I only have experience using highly dilute HC-110 using roll film with some good success. I would embark on learning the ZS or BTZS methods of "exposure and development", it's pretty cool.
Chuck