67 Dart daily driver........undercoating

I like a nice clean undercarrage painted too.I would try chipping off the undercoating with a putty knife first before applying heat.From being old it might just comeoff in chunks,but if not using a small torch sure makes a heck of a mess.I would still undercoat wheelwells,torsion bar area and rear leaf area.Any area that these Canadian cars start to rot should be coated.Good luck.