Some people leave the outside frame alone and remove both the inside frame.I cut a notch out of the frame then tac welded the boxes in place for alignment to make sure springs are positioned properly.RMS sells boxes with multiple front spring holes for ride height(around $100)The hardest part for me was drilling out the rear frame for tubes,with the spare tire well in the way.I used a 90* drill for this and a 1 inch metal hole saw.Here,s some pics to give you some insight..
Oh I also moved my rear back 1 inch for a 15x29 inch slick:D View attachment car pics 66 Dart 085.jpg