87 mazda b2000 with bodydrop and drop spindles,what offset do i need

i got a 87 mazda b2000 im in the process of bodydropping with drop spindles but need help on finding rims and offset.i know if i ran with 20x8.5 i would need a +40 offset but if i did a 20x8.5 with a +38 offset and 4wd fenders and bed would i have enough clearence with the fenders where i wouldnt rub?? also was thinking about running 18s and if i did 18s what width and offset would i need to clear with those rims?im a lone minitrucker from alaska and need all the info from you guys to help out.

Convert it to 5 bolt, run a 20x7.5 or 20 x 8 with as high an offset you can get.  I sell 5 bolt conversions and I am in British Columbia, so not to far from you.  Email me for more info and pricing. Clint www.nolimitscustoms.comnolimitscustoms@hotmail.com