14.5 is not overcharging an auto starting FLA battery - and the battery itself and running loads would determines current levels are being supplied & that would be what would load up the alternator. Remember when the battery becomes charged it rejects current input and might not clamp the regulated voltage down so what you're seeing is normal. Without charging the battery the alternator is not doing much work at all.
I've changed the internal regulator on an LT-1 Camaro way back when - it had an annoying habit of causing all lamps to dim deeply and then spring back up about 15 seconds after starting the motor. The Chevy dealer sold me the part and I did the job under a streetlight at night, it lasted 135,000 miles and was on the second battery when it was traded off. Unless you know what the OEM part spec level is you might not be getting an improvement.