Alternator/regulator upgrade

Lord Sparky
Thank you, I'll check the Crackedback's wire options.

67Dart273
Thank you for focusing me on determining the problem rather than working out where to source each spare part in the system.
I did some testing; while running at idle the battery voltage across the terminals was 12.6V and from the negative post to the alternator output stud was 14.6V.
I then borrowed the battery off my son's '72 Satellite and these two voltage measurements were pretty much the same again. I didn't get around to raising the revs to cruise level, I'll get another set of hands to help with that. Neither battery has been tested, I'll get the Dart battery done to be sure of condition.
I checked voltage from battery positive to alternator stud and it shows a volt drop of 1.9-2.0V as expected (14.6-12.6=2.0). This is suggesting too much resistance between battery and alternator?
Looking at the wiring diagram, the two heavy wires on the alternator stud run to the horn relay (purple) and to the ammeter (black), is that correct reading of the diagram?
There isn't a direct wire from alternator to battery?
Is this where the discussion on bulkhead connector condition comes in?