I don't know what diagram you followed but a basic '65 Dart generally has no extraneous wires, at least for street use.
Also '60 amp' rated alternator is not original but knowing that may or may not be important.
What are you trying to accomplish?
Pishta is correct. Higher output alternator is generally not going to put out any more current than a stock unit - except if the battery has been drained down. IIRC '65 a-bodies have a robust pair of connectors for the main feeds, so that and the ammeter run should not be a problem - again depending on what you're doing.
Not sure why Brian posted a diagram that looks like its for Aussie Valiants. But the concept is pretty similar.