Charging issues on a ‘64 Valiant...

Did you properly wire in your new triangle-plug regulator? It's not a direct drop-in for the pre-'70 regulators, and if you try to treat it that way you'll have a no-charging situation. If you want direct drop-in electronic, this dude is your best pick. While you're at it, run a wire from the alternator housing to the regulator base, and from the reg base to battery negative. And even if you did change the engine bay wiring to accommodate the '70-up triangle-plug regulator, the regulator must be grounded (bolted to the firewall) in order to function, so if you just left it hanging and started the car to check it, that wouldn't work.