1979 Dodge Cobra remodel....Welcome to help suggestions

Thanks for posting the pictures! Looks like you're making some decent progress. The paint work does look quite successful--I assume you sprayed?

I would check the furnace heat exchanger very carefully; it doesn't look very confidence-inspiring to my untrained eye. A leaky heat exchanger is, of course, a rather important safety hazard, mostly from the possibility of CO poisoning.