Cab corner and other rust questions?

[coltfan]

I am looking at a 63 chevy truck that needs a new passeneger cab corner. I know the corners are readily available, but what I need to know is how far up the commonly available replacements go. I am concerned I would have to go up quite a ways to find good metal. I want to know how tall the corner patches are. And also which ones are the tallest. I have looked online, but it is hard to tell.

I am not concerned about patching the floor, but the opposite end of things above the windshield has me concerned. It has 2-3 spots of roughly 4-6 inches of pretty good rust bubbles. What is the best way to fix them? I can probably remove the rust easy enough, but fixing what is left after the rust is gone is what I don't know about.