Overcharging 68Dart...need some short fused help (pun intended:)

capnswanny said
I'm going to pick up an 30A ammeter gauge tomorrow,

Inductive clamps are fairly common these days.
That's one option. A short discussion in this thread.
67 Barracuda alternator with 2 FLD connections
Here's another one
[FOR SALE] - MAC TOOLS EM110 inductive pick up amp clamp

There are some other versions too. Used to be pretty common underdash gage (For those Chevies that came with nothing but a gas gage and a speedometer). I know I have a couple of those as well.