Here’s what I’d do…
Take a big wire brush and brush the heck out of it.
Spray it down good with engine degreaser.
Then put some MEK, Acetone, or Lacquer Thinner in spray bottle and spray it down.
Wipe it down with a clean cloth.
Spray a coat of good metal primer (Rust-0leum), let it dry well, then spray it with a good coat of Rust-Oleum for metal.
That should be good for a LONG time.
Gnarls.
