Check Rustoleum's product line.

Because I want all that "history" and colors to show thru and keep the dust from the old paint on the wall. I'm personally undecided about painting it or no but sooo many people love that wall as is. The clear coat will seal it. I thought I will live with it for awhile clear coated.

Painted my 20 yr old pine cabinets white about 3 years ago, I had glass put in a couple of the doors. After weeks of the process, taking doors, shelves out, cleaning, degreasing, sanding, prime, sand, prime, 2 coats of white-I used Benjamin Moore's cabinet paint, it wasnt recommended to coat with a clear coat, unless you want a shiny, plastic type look...I read forever about this process. To this very day, they look wonderful and clean very easily, just wipe off, no nicks. I think having no shiny clear finish makes them look like a rich, thick, white. By the way, I did buy the 30 dollar paint brushes I had read about, but found thru the process....honestly those little foam rollers, and brushes gave a smoother finish and I could toss them at the end of the day.

You probably need to reduce the mosture in the air in the bathroom with a good exhaust fan. If the ceiling gets wet enough the steel will rust again no matter what kind of paint is on it. You probably should have used PVC corner beads to reduce the risk of rust.