alternator pully swap

Thanks for the replies, you confirmed my thoughts I would have to disassemble the alternator to press the new pulley on. Time to learn something new to me.
As for determining the output of this alternator. If I take it to a tester that can spin it will
they be able to tell me more than "it's working" like what amperage this is rated.
It is a square back alternator and I would guess when it was rebuilt they jumped up the output from what it was born with but would like to know for sure.
I am trying to prevent the alternator from spinning to fast on a quarter mile only car.