Pulsing dash lights

This can be a form of voltage feedback due to poor grounding or harness voltage drop, so main causes are

Indeed, VR especially older mechanical regulator (69/ earlier)

The usual drop in the ignition circuit, bulkhead connector, ignition switch and connector etc

Or poor grounding at the VR to battery

Try making up a good big alligator clip lead with big say, no12 wire. First try clipping from battery POS direct to the junction that feeds the VR and ignition, and if no effect, jumper direct from battery NEG to the VR mount. AKA nearest bolt you can get to, and clean and re-tighten the VR mounting bolts, firewall, and rear of VR