Yes find out if you have a full current ammeter or the later "external shunt" type. So far as I know the easy way to find out is to examine the ammeter, stick your head up in there. The full current ammeter will have stud/ nut connections and large gauge (no10) red and black wires.
The external shunt one will have quite small wires.
Pull apart the bulkhead connector and examine the terminals for damage, heating, corrosion, fix as necessary. You can get new terminals for that
If you feel like dropping the column and pulling the cluster, there's a few things there, but generally it can wait
Next you want to worry about voltage drop in the charging/ ignition switch circuit, because the drop will actually cause the battery voltage to run high when the car is running / charging
To find this out, turn the key to "run" with engine stopped. Find the light blue wire with the "push on" flag terminal connecting to the field of the alternator. If you cannot access it in place with a meter probe, pull off the green wire and swap them around. Electrically they do not matter
Now, stick your voltmeter probe in so that with wiring connected normally, you can contact the blue connected field terminal of the alternator. Next stab the remaining probe into the top of the battery POS post. You will read a voltage, the LESS the BETTER. If you read over .3/ .4V (3/10 of one volt) investigate why. "Usual suspects" are the ignition switch, the switch connector, and the bulkhead connector and parts of the ammeter circuit if it is the old style.
Every bit of voltage you measure, when added to the normally operating 14V VR, will be additive.
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Next, check the ground circuit. This time, warm up the car and run at fast idle, and make this measurement first with accessories off, and again with lights, heater, etc powered on. Stab one probe into the top of the battery NEG post, and stab the other--HARD into the mounting flange of the VR, to get through chrome, paint, rust. Once again, you want to low voltage, the lower the better, zero is perfect.
Better ground bonding between the battery or block and body, and bettery grounding of the VR to the body is the answer. You can also add an auxiliary ground lead using no12 wire or so, from one of the VR bolts to the engine block.
Same is true of the electronic ignition box. You want a good ground from the case to the body.
Other than that, overall wiring health. Check out grounding of parking/ tail lights, rust in the sockets, etc etc.
