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 http://www.a1.nl/phomepag/markerink/irfilter.htm (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 http://www.pauck.de/marco/photo/infr..._of_films.html