What is the highest amp rating alternator I can use on a 1970 Dart

An alternator shouldnt cause anything to catch fire or smoke. ...................a friends 82 suburban ran 2 250a without a problem.

*Some are externally regulated which if you dont regulate will cause a battery to charge over 12-14v which can hurt electronics*

Upgrading your charging wire off the alternator is a good idea. Factory thin wire will restrict current causing it to heat up and can burn. The factory wire is only there to handle what the factory alt puts out.

We are not talking about Shovvies here. We are talking SPECIFICALLY about old Mopars which have their own specific problems

Mopars are the ONLY vehicles which, in the case of cars into the late 70's and in the case of pickups and vans somewhat later, used "full current" ammeters fed with the flimsy bulkhead connector.

The "full current" ammeter and the bulkhead connector, AS WELL AS wire size are all problems in these old girls