No faking when you're doing historical work. You can't do it right unless you know what you're seeing, how it was made, why it was made that way, and how it became the way it is now.
There's a lot to learn from every piece of old metal work. Tools have changed, materials have changed, and techniques have changed. The challenge of every historic preservation, restoration or reproduction project is to see how it was done and the best way to do it again with respect to the original article.
In many cases, the original, historical material is just as important as the design and craftsmanship and it should be preserved with only the most minimal and unobtrusive repairs and replacements.