Rust on Keel - how to proceed?

[LiveCat6]

Hi All,

First time posting.

https://imgur.com/a/XaTY0mr

Purchased this 1980 CS Yachts 27 footer last summer. Now that it's on the hard i see some rust in a criss-cross pattern on the keel where it seems to connect to the hull of the boat.

What should I do about this?

Also I'm planning to sand my antifoul down and re-apply anti-foul before launching in the spring.