I reckon you would want a 100amp alternator to sufficiently charge the batter and run all the cars electrics and now and large called load of the electric powers steering pump which was never factored into the design of the original alternator. The alternator is there to power and run the car. Ultimately the battery is just a starting device.
If you have access to a DC clamp meter and a multi meter it would be A good test. Have the headlights on and the car running use the power steering and see the voltage and current on the alternator output.
Then use the clamp meter on the electric steering pump when activated and that will give you a good idea what the whole car needs to run average wise. You will probably find tje alternator prob around 80amp or less will be at max or close too I reckon. It's a good test for even reliability reasons you don't want it to stop charging while your driving.
