need some nissan wheel offset help!

im totally new to the whole nissan thing. my son is building a nissan extra cab. we are sfbd it on 20s. we are having a set of one-off billets made but the designer needs the offset, bore, lug pattern, etc... can you guys help a brotha out?

btw: here is his thread for the build-

http://www.streetsourcemag.com/forum/topic.aspx?method=reply&topic_id=104638&forum_id=85&M=True&S=True

thanks in advance for your help!

for keeping it 6 lug u need no more than a 20x8.5 and no less than a +40mm offset. also need a 100mm bore(4inch)