I did the same thing, as n10, to my 68 280 se coupe last year. I also put dynamite inside the doors and behind the front kick panels (inside the fenders). At the same time I replaced the all of the carpet and the floor pads. The interior looks great the outside noise has been reduced. Most importantly my 300 watt Kenwood with front and back 6 inch speakers and 8 inch sub-woofer sound amazing. The work was well worth it.

__________________
Britton McIntyre

68 280 SE coupe 'Hairball'
70 280 SL
71 280 SEL - RIP May 2010