68-70 B body is only 3/4" wider overall. You can move the springs easily. Move the front mount flush to the rail. You'll need to drill a clearance hole for the spring eye bolt. If you remove the rear bumper/bumper shocks the rear hanger can be moved inward and forward to the ideal location by simply drilling holes. use the B-body lower shock plate as well. The only part of the wheel well that's in the way is the outside front of the inner right behind the rear seat. A pie shaped piece as a filler works . The rear seat will still fit if you desire. Now a 10" wheel with a 10.5x29.5 will fit at normal ride height.
Doug