I have a little gizmo for working out the exposures for large F stop numbers like F150. Very easy to use and I find it great... Let me try to make one for you
I use Ilford HP5+ for my pinholes. I rate it at iso 200 and dev in xtol or id11.
ID11 seems to produce the better negs for print for 4x5 pinholes. My times in ID-11 are 1+3 for 13 mins. NOTE: I only ever shoot pinholes in bright light. At F132 which is near F150 this gives me an exposure time of between 1 and 10 seconds but its normally 4 seconds (these times include reciprocity failure). My two reasons for using HP5+ are that its available in Gunns at a good price and it also has lots of exposure latitude