Anyone have any input on what coolant flush they have used to remove rust from the outside of sleeves?

I was pulling my head to change a HG on my car and on the outside of the sleeves is a some rust. I have seen a few products out there but some of them are not very kind to aluminum.

Needing some input. Putting the new HG on, reassembling everything, and then going to flush the system to remove the rust is about the only thing I can think of to do it effectively.