Good ol' previous owner... He was a nightmare on me too... Doesn't look like too bad of a project, you may have caught lightning in a bottle! A parts car, a couple weekends and a beer or two and the car could be looking brand new!
I'm glad to see the damage wasnt too bad. All that melted plastic can make quite a mess. I should know. I had something similar happen to my 84. I'm happy to see you're fixing it.
Note that even when done.... Burnt smell can still take months to years to be gone. Worse when gets humid or heat in on.
Reused carpets etc hold the smell of smoke, mold/mildew, etc. You can try using Fabreze etc to stop odors in the padding etc before you install them.
Heater/AC box is hard to clean out too. Clean outside and inside the box while dash is out.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)