Back spacing for my new wheels? any help and or pictures would be appreciated thank you

I have 60r/255-15 on the rear of my 70 Duster want to put 15by7 on the front need to get the back spacing right want the outer edge of the front tire just inside the fender well any help and or pictures would be appreciated thank you also the 15 x 7 on the front would be a 60 R/235by 15