If memory serves me well, that vdo clock has an internal fuse which amounts to a tiny wire behind a lump of solder on the back.

Hopefully the fuse box fungus is limitted to the fuses and their brass brackets, so you dont have to disconnect the entire box. Hell, you'd be out of your mind to remove the entire box and be left with a bunch of wires to sort out. Coca-cola works well at cutting through electrolysis corrosion.

Decent stainless screws for headlight doors should be available at hardware store or boat marina. Probably the toughest part of fender replacement, aside from pulling the bumper, is accessing one 9mm bolt at/near the driver's door upper corner area.

Gatling-gun engine sounds scarey. How are the valve seals and guides? Any start up smoke?