[HardcoreZ28]

Sounds like a good plan all around and the extra bracing will pay off when you upgrade the engine setup.
For the undercoat removal...take off as much as you can with the scraper and heat gun...then you can use a rag soaked with kerosene, gasoline, or brakleen to remove the light stuff that's still on. Just don't go back at it with heat while there are fumes are residue around.

Oh and wear a hat and goggles when you're doing the job. Melted undercoating is hot and sticks to your hair....and if you get POR on your face it could take a couple days for it to come off....been there and done that.