1972 Canadian H-Code 340 Dart Swinger Special Resto - Finally started!

Awesome job in all aspects of your build. I did a so-so job on 67 ac/heaterbox restore.
But looking to do a better job on my 69 (non ac)
The Top Kote, was that used for rust prevention? (Humidity/condensation)
Were/are the boxes safe to dunk in the EvapoRust?
One more question, the Matte clear. Spray bomb? Concerned about comparability with the fiberglass.
Thanks again, inspiring work.