A popular way of removing the sound deadening without (much?) scraping is using dry ice and smacking it. I've used a heat gun and scrapers. After being so old, most of it was detached anyway.
I went nuts years ago with neons and weighed so many things. Maybe it will give you some ideas on how much something may way or what you could remove.
https://forums.neons.org/viewtopic.php?t=278316
Just about everything was weighed on a digital scale I use to ship things that's nearly identical to the weights of things I ship from UPS/Fedex/USPS. You may find that if you weigh something, other people's weights are way off.