Clean it up & wipe some Ospho in it. Available from Kelley Moore paints for $12.00ish. Thatll kill the rust. Get a piece of vacuum line & run an X-Acto blade the length of it, then stick the tubing on the edge of the lid. You may need some contact cement to convince it to stay & maybe some tape to hold it while the glue sets up.
The Ospho is a good thing to have around, its not like you would be tossing $12.00 on this one thing. Someone else may have a better idea for the cleanup, thats just the way Id do it, cuz I always have Ospho on the shelf.

Thank you--that's my next project! Appreciate the tips.