Donald Qualls
Subscriber
I'm still trying to distinguish between the characteristics of the films on offer, but the 'Fuji PT-21 HR-II Medium Speed Low Contrast' sounds interesting.
For microfilms, "high speed" is ISO 32-40 by the time you develop to low enough contrast to have a good gray assortment. Medium speed should be ISO 16-25 range -- but you might do better with this, since "low contrast" may not require you to use special developers or massively underdevelop by the film's usual standards.