I am sure they would fit with the spacer, the fender prob. wouldn't need cut or rolled. 4" of bs with a factory dimension rear should set you up a little better than the 4.5" but with the spacer your good either way.... You have aftermarket wheel studs or factory?? Pretty sure the factory offset on the monte ss wheels I am using now are 3.5" of bs and I could run a 275 w/o rubbing with no spacer and a factory rail and fender lip... If anything you will be too close to the frame with the welds your wanting to run...