Maybe this will help some:
I have the leonardo pinhold camera. This was part of the instruction sheet that came with it.


4x5 camera

focal length pinhole size F stop

1.5" ,010" f150

3" .012" f250

6" .017" f352


8x10 camera

3" .012" f250

6" .017" f352



approximate times for exposure using tri-x film in bright sun:

1 1/2 " camera 2-3 seconds

3" camera 4-6 seconds

6" camera 9-14 seconds

From there your best questtimate would work