I used Caswell. Reason being, it doesn't require the tank to be "sterile." It advertises that it actually bonds even better to surface rust. I have read too many horror stories about Red Kote and others peeling because the tank wasn't "perfect" before application.
The Caswell bonds to the plastic baffle also. The only requirement is to knock of the thick, flakey stuff and rinse out the tank with acetone. When I was done, the tank felt like it has a plastic shell on the inside of it.
[This message has been edited by USMUCL (edited 01-31-2019).]