Don't jump to conclusions.
It could be any place in the line.
67 Barracuda has a different meter build than a '70, or '65 or even a '67 Valiant.
The most likely scenario is something to do with the most recent change.
"has new wiring"
Exactly what was replaced?
We don't know. But now it doesn't work.
Go find out where the power is and is not present.
Take a voltmeter and check at the fusible link.
As was suggested, check for power at the alternator output stud.
Then under the dash, use the voltmeter to check for power at the bulkhead cavity for the battery feed, and at the ignition switch. Those are the easiest to access and will tell you where to look next.
Be carefully about your probing. don't wear jewlery and don't stick wrenches etc into wiring areas since using the voltmeter you are doing a check with battery connected. All main circuits are HOT.
Schematicly the power feeds look like this. Check systematicaly for where there is power at connectors that are easiest to access.
'67 Barracuda power and ignition wiring diagram showing connector cavities:
Understanding Charging Systems with Ammeter, Diagrams