The optimum pinhole size for infrared will be about 1.34 times the diameter that is used for color film.

I use Cachet Macophot 820c and either a 29A or R72 filter.

Transmission specs for filters can be seen at (the R72 is about like an 89B)

In the summer sunny 16 - between 3 hours after sunrise and 3 hours before sunset,
set your hand held meter at ISO 6 (29A) or ISO 3 (R72) to start. You may get better results hitting it harder and developing less than recommended. (My gut feeling is that the recommended development is at least a one stop push).

I've found the reciprocity of this film to be about 1 Stop at 2 minutes (i.e. expose for 4 minutes if you meter for 2).

You may see a comparison of different IR films at