AMP instructions vs Ammeter help!

Although I've read that there is a difference between an ammeter and an amp gauge
No. Maybe in some specialized situation, but if so, not typical.

( AMP METER INSTRUCTIONS)
If you are using an Amp meter you will need to route the 10 GA Solenoid PWR=Red wire from the fuse panel to the amp meter and then from the other post of the amp meter out to your positive BAT source.
Some automobiles use a remote 'starter solenoid' for the heavy battery cable to connect to the starter. Chryslers have a remote relay in the same location, and the heavy cable goes to a solenoid on the starter. Knowing that, here's what your instructions tell me.

oddAMPinstructions.png
Now this doesn't fully make sense. The ignition switch and headlights are not normall on the other side of a Chrysler fuse box. Is this harness use the origonal fusebox or its own? Also, in the mid 1960s a fusible link was placed in the circuit from the battery.
Some info here: Understanding Charging Systems with Ammeter
New to electrical so in English please, ready to fire her uP & don't want to melt her down!
Post up some photos - I personally don't know what instrumentation is on your '64 Dart. Not everything stayed the same from the first A-bodies to the last, and I don't want to guess with your '64; And none of us can guess what this aftermarket kit includes..