Hey there welcome..for a stored vehicle she looks great. Most people do one change... from a 3 tree, to a floor shift (easier I guess) your manual tranny Is more popular than an auto. When you start to do the suspension work, post pics If you could so others could see what you did, how you did it, and the end result with the products you choose. As for the rust issue POR 3 seems to be the way...stops progression dead in its tracks. You could take her to a local body shop and see what they say about the issue and how they would deal with it and how much. Get enough info from them and if your handy....there ya go.
1965 Bel Air
Honey the garage is mine, you get the rest.