I needed more amps too, but took a different route. I had my squareback, dual-field alternator's stator rewound and heavy duty diodes installed at the local alternator shop for under $200.

Of course it bolts right up to the stock mount and looks bone stock for a 1970. It puts out 70 amps at idle and just over 125 amps above 2000 rpm. I upgraded the wiring and did the bulkhead/ameter bypass sugested in the article on Alpar.