I have never been one to be fascinated with "numbers matching" or auto provenance. My preference is to use or enjoy machinery whether its a tool or a vehicle. 
Since the firewall is black, a cad colored brake booster would have added a little contrast that would have made it more visible. 
I'm not knocking your artistic license since I respect and admire your work. 
When I get the time, I hope my projects look half as good as yours.