Tar-like undercoating on 63 Valiant...any way to remove it?

We did it with a propane torch and putty knives. Heating the undercoating and scraping it off.
Started out with a heat gun but found a propane torch was faster. My kid just getting started on it.
Going to be his car after all...
ZdcJoByb5_0Kmn0MjiLZLaF=w1430-h804-s-no?authuser=0.jpg


xUCL2US2jw4WkgaEAM7bOeu=w1430-h804-s-no?authuser=0.jpg
It was a bit of work but effective. It went to media blasting once we had the undercoating off.

Next time I may try this Dry Ice method or just do it in when it's very cold out...
I've also seen this done with the car right side up and the dry ice on the inside to get it cold and chip it off in chunks.