No. 2. 
You may need some of the panels even if you X-ray the next one. You have learned the 3 most important things to look for in a project purchase. 1. Rust, 2. Any rust? 3. how much rust and bondo?
I think you must be exaggerating about $2000 for just cab patches. No one would do that even if on meth.
Most of us have been there or at least somewhat there.
You will find a cab 55-59 that will be nice and solid for $600. Sell the patched cab to an energetic lad.
Leave the past behind where it belongs. If we were buddys, I would be calling you some names. But out of respect, I feel your pain/frustration. If it's not fun, change it.
You will be able to sell the unused patch panels, at a discount, to recoup, if you wish.
Next time take a magnet and an ice pick with you. Knock on it. Sight down the sides. It's not easy to determine how much rust. You did the right thing by sandblasting.
I do not know how much there is left to fix. I do not know if you did a good job, I do not know if the doors will ever fit. I know there are plenty of good 55-59 cabs still around....so that's why I chose no. 2. If you have to buy a whole truck to get a good cab, that never bothered me. I sell the hell out of the parts and I have room and can hide them from "she who must be obeyed."
