I found this in the MCA judging rules for '68's: "Hood Hinges and Springs; original style. Phosphate and oil finish." The closest I have found to achieve this is an aerosol called CAST BLAST, by Seymour paints. I also use this color for the hood latch pieces. It's a good finish, and contrasts nicely with the predominant black surfaces. Hope this helps
Neil Hoppe
If you don't mind spending some time there are ways to achieve the original look.
The first way is to use gun bluing which you can pick up at wall mart, then after you achieve the correct look, just rub it down with some cosmoline.
I prefer to do parkerizing. The link below is from a company that sells a great kit to achieve a very close factory look.
http://www.calvan.com/html/large_black_kit.html
For those that prefer to make a home brew, see link below:
http://www.finishing.com/121/03.shtml
Don't forget the correct bolt kits from AMK.