Alternator Amperage Question

What the factory used might depend on your car's electrical options (and not the engine). In your points days, I think 35 A was standard, so unless your car had a spotlight or powered convertible top, that is probably what it had. I don't think you can distinguish from the outside, difference was in the stator coils.

60 A shouldn't threaten your wiring if it is pristine. Most aren't, and even a 35 A alt melts the big ALT and BATT feed-thrus once they get a little corrosion (i.e. CT). Clean terminals, read-up on MAD Bypass, etc if you don't want that to happen to you.