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

I tried using a heat gun and then a propane torch on the Dart, nothing would touch that crap. I got a needle scaler and that did the trick. This was easily the most filthy job I've done on the car. I had a face shield, eyewear, a quality dust mask, hat, long sleeves, and still it got everywhere. However, when done it sure looks nice!

The grey area is cleaned off of old undercoat, the brown is the primer.

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Shore looks purdy all finished up with new undercoat!

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