Those "sound deadner" kits are junk. Die cut flimsly graniy stuff that barley covers anything.
Do yourself a favor and go to Home Desperate and pick up a roll of Tri Ply, or rubberoid modified roofing, comes in a roll, and you can cut and weld (with a butane torch) this stuff to conform to the entire interior, I just did my 67 Coupe , every sq. inch, and my car sounds dead and tight as a drum.