Battery cables -where does the negative go?

Okay folks- I went to my 66 Barracuda “s”
Parts car for the correct bolt to mount it to the head... there’s no bolt, not even drilled for a bolt. It’s under the spring return for the carb. I can bolt it to the new engine for my car to that point but something it telling me that’s not correct factory point for a formula S car. No offense but my parts car is all original. Never been apart. Engine is actually red not orange in photo- cheap camera. View attachment 1715240082
Joe

View attachment 1715240081

wouldn't an original 66 273 have been red?