What Alternator 1981 Ford Fairmont 6 cyl 3.3 L

What is the correct alternator for a 1981 Ford Fairmont
6 cyl 3.3 L. auto transmission. No air conditioning.
No large audio amp or anything like that. Nothing
extra.

Listed is a 60 amp and a 100 amp alternator.

Hypothetically say my vehicle requires the 60amp alternator,
what problems if any will I create if I install the 100 amp one
if it fits physically.

Will I overcharge the battery?

Thanks in advance
Denny B