Steelerfan, an alternator will only produce what is required of it. Amperage is the amount of load an appliance has on a circuit. That appliance is what draws the amperage to it, for it to function.
If you have a cig. lighter plug, for example, it has 12V (voltage, remember) and with nothing plugged into it, there's no load (12V, 0A). If you put your 12V space heater on it, you're going to DRAW amperage through the wires to the heater. The alternator will produce it, but not if there's no reason. Your heater is what will make the wiring fail. It's when you put aftermarket things on the factory wiring (that wasn't designed for it) that draw a lot of current, that you run the risk of damage.
In other words, the stock components won't draw any more amperage than they used to, so that wiring will be fine. If you add on, put in new wiring for that item that has an appropriate rating.
Components don't take power, they use power.
So far, if I need to replace an alternator, I've gone to the parts store, gotten the "biggest" alternator offered for that model to replace my usually puny one, and been on my way. It can't hurt to have the extra potential there. I have a 140A alternator in the truck, and you should see the needle go UP when I use the winch. I'd like to have all the amperage available when it asks for it.