rims for a nissan and bd on 20s

i was wondering what offset and backspacing i need to tuck on my 95 nissan and do they have to be fwd to run 20s all the way around.i want to bd it on 20s and i know i have to tubb the firewall relocate the battery, brake booster, move the clucth master cylinder up and extend the wire harness is there anything im forgetting help me out if you can