Think you'll need a 80 AMP alt like the 70's cars had with the electronic ignition, don't think the 60 will be enough, even going 100amp won't hurt anything but you'll have plenty of juice. Here's a calculator: Calculate the Amperage You Need
70's cars DID NOT come with 80A alternator unless they were the large frame optional 105A setup which was HUGE. Saying "won't hurt anything" is uninformed. There are MANY cases of the stock bulkhead connector and ammeter failing with LESS than 70a alternators.
