Well finally got everything disassembled today and there ended up being a little more rust than was visible once I took the sides off the cart. I am kind of upset at myself since I paid 150 bucks thinking it was in better shape.
One thing I also noticed was there appears to be some rust inside the square steel that makes the frame. Is this off any concern? Is there a remedy to it?
There was a lot of rust inside the frame of the Genesis Silver B I restored (didn't actually fully restore it, just cleaned and repaired).
I shook out the loose rust and then sprayed Rust-Oleum Rust Reformer liberally from each open end of the tubes. This product is supposed to be a rust converter, is fairly cheap and has the advantage of being black so it doesn't matter much if you get it where it shouldn't go.
If I were going all out I'd use Eastwood Internal Frame Coating which comes with a 24" long applicator which would be ideal for the frame tubing.