Rusted Fuse Block

[Arreaux]

I inherited my 67 from my late father and I have been putting some time into lately. Well I was going to install an HEI and wanted to connect the power source to the terminal block on the firewall. AS I started to remove the retaining bolt it just spun around and around. No big deal just go inside to see what's going on and this is what I saw of the fuse block....

I was not aware that these thing can rust?
I'm hoping it can be salvaged?

I also discovered that the retaining bolt that would not come loose has some corrosion on the blind nut and just spun around. I did mange to get it loose with some help from my son. When I removed the terminal I see a lot of corrosion in the connectors.

I was wondering if some dielectric grease would help prevent this from happening again?