will 3 1/2" offsets fit? Alum slots on 74 Duster?

Ok- so I am not going to get the 14" slots. Will there be fitment problems with 15" alum slots? Someone posted earlier about the 14's will hit the caliper unless you use a spacer- then it will scrape the fender. Will 15" slots scrape anything without spacers? I may be able to get 15" slots for $50 each. If this keeps up, I will just try and find some 15" Ralleyes and call it a day lol
Im posting this on the main board also to try and get more opinions.