Ross, if the stator is upgraded, that is fine, but the rectifier assembly also needs to be upgraded to else the alternator is going to fry itself in a heartbeat. So, before you buy that bigger alternator, make sure the rectifier (diode) assembly is upgraded too. Else, you are going to use the alternator good a few times and then the rectifier assembly is going to cook itself and fail.
As for the truck stopping when the doors were locked, what essentially happened is you were running just on the battery and the voltage got low enough that the COPs couldn't keep the engine running. You could have gotten the truck home by yourself if you had someone willing to put a partial charge on the battery using some jumper cables (about 15 minutes with the jumper cables connected between the two vehicles and theirs running). That would have gotten you home provided you kept everything else off.
As for the 6 gauge wiring being "thick enough" (that's what she said, LMAO), all the manufacturers these days use the "bare minimum" wiring for a given application. So, Ford is already near the limit of what that 6 gauge wire will handle. Now, you are going to add another 50% worth of current carrying capacity there. Doing some number calculations, you are going to be dropping 0.8 VDC just between the alternator and the starter solenoid. For a wire like that, it is a lot of power loss. Not to mention, that wire is going to be dropping 160 watts of heat (think about the heat a 150 watt light bulb gives off, that is the heat that wire is going to give off!!!!!). Will the truck work, yes. But it will work better with the heavier gauge wiring.
200 amps is a lil more hard to find. I found the following with a quick search...
