Not sure about that. More along the lines of the B-body for width. The B-body 8.75 being almost a drop in. The rest of the rear suspension on the M's leave a lot to be desired, even if you have the rear sway bar like mine does. The rubber iso's on the rear springs have to go. The rubber bushings on the front of the springs leave a lot of wiggle room, literally, on the *** end. Firm Feel is making adapters to bolt in E-body springs for 'em. Not sure if that's the way I'm going on not...he he. Stay tuned.
There is some A-body stuff that is almost a direct bolt in. Exhaust is one of 'em. TTi's headers will bolt in, as well most of the pre-bent stuff from Summit or Jegs. Just need to move the gas tank on the M's one notch over on the straps to hang the duals.