I ran into the similar problem with my project. I bought a couple reall cool but very expensive tools.
The first one i bought is to measure wheel back spacing. This enable me to test fit my wheels before i spent the money on the rims. Once i mounted the wheels up i notice that i was going to be hitting the inner fender and that i would need to roll the fender lip and remake the inner fenders
here's a picture of the "Wheel Tech" tool
The other tool i purchased was to roll the fender lip
http://www.tirerack.com/accessories/tools/fenderlip.jsp