So, my revised goal for this car: 1) get it up and running 2) make it look decent and 3) not worry about making it a show-piece car.
The two chassis paint product manufacturers I've found for rusty metal were POR-15 and Eastwood. Reviews for the two products are mixed but for me the youtube video from Eastwood showing the results was the deciding factor.
I purchased the satin finish rust chassis paint set which includes the rust converter, rust encapsulator primer and chassis paint for $100 off Eastwood's webiste. Before using this on the chassis, I decided to try it out on the gas tank, which could use a new paint job (below is a picture of the tank, partially sanded).
First, I sanded and wirebrushed the gas tank to bear metal and surface rust. Then prepped the surface clean with denatured alcohol and applied the rust converter to one side of the tank. I went to do the same to the other side however realized afterwards that I had accidentally applied the rust encapsulator thinking it was therust converter. Annoyed at myself, I decided to wirebrush the encapsulator paint off when it dried, but noticed it was adhering to the metal really well.
As I was wiping away the small amount of paint dust that had accumulated, I accidentally brushed the converter side of the tank and the converter paint dissolved to dust and was coming off! The Eastwood website had mentioned that they do not recommend using the converter on good metal and now I understand why. The converter only adhered to the parts of the tank that had surface rust, but everywhere else the converter paint brushed off.
I decided to leave the the accidentally-applied encapsulator paint on and use 220 sandpaper to remove excess converter paint and apply encapsulator paint. The satin paint finish went on smoothly without issue (thank goodness)and I'm quite satisfied with the end result. In comparison, a new tank from Victoria British would have cost me $199.95.