I am more familiar with San Jose cars but I don't think these details varied between plants so I'll give it a shot.
• Four firewall mounting bolts for export brace
zinc dichromate (gold)....and I am assuming you mean the two braces to the cowl, which I don't think would be considered "export" braces?
• Three studs and nuts on shock tower side of export brace
phosphate and oil, so a grayish flat black
• Front shock tops
on a Dearborn (this one is plant specific) car, phosphate and oil
• Hood hinges and springs
phosphate and oil on the hinges with the springs likely a different (darker?) color since I think they were just tempered/oiled.
• Hood latch and bolts
P&O on the latch and I am going to say zinc on the bolts (silver)
• Four bolts above hood latch
Two inner ones are P&O and the two outer ones are zinc, though this one is controversial and someone will disagree with me here.
• Top of fender bolts
zinc
• Ground screws near wiper harness grommet
Hmm, on shaky ground here without checking, but if you mean a fairly large sheet metal screw I believe it is P&O
Edit: large screw zinc dichromate small screw zinc
Some of these that I noted as zinc might actually be cad plated but for your purposes all you need to know is they are silver.
You should invest in the assembly manuals. They are a great guide to the finishes on most of the components and fasteners.
