vickraft...Welcome to Stovebolt. Like Blake said, sounds like you have a great plan. To answer your question about cleaning behind the dash. I haven't gotta that far yet, but my intentions are exactly what you mentioned. Behind my dash isn't too bad...just surface rust. So I was just gonna wire brush and sand by hand then use Zero-Rust afterwards. Before working on my truck, I've never heard of ZR, now I'm a big fan of the stuff. It really does perform what it says it can do. Don't worry about getting it down to bare metal behind the dash.
Keep us posted on your progress, and don't forget to show us some pictures.
Have fun...
~Ron