Those are great suggestions fellas, thank you both. Let me say again, this fuse block is a rusty mess and by all rights should be replaced. If I'm successful with the clean-up, I'm certain this is a band-aid fix before the ultimate replacement solution.
So, I got my hands on a donor fuse block and tried a Dremel tool. It's basically a round grinding bit. It fits the fuse clamp quite well, especially the rounded arc of the clamp where the fuse makes its connection. The bottom fuse holder was cleaned with the Dremel tool and the on above wasn't cleaned. There's a notable difference as you can see. See the attached photo. GM Fuse Block Cleaning
Do you think the Dremel tool is too aggressive? I plan to follow-up with some dielectric grease on the fuses to slow the subsequent and inevitable rusting process.