Powermaster has 2 basic offerings. A square back case rated ~75 amps and GM guts in a Mopar compatible case rated 140 amps. Both are available in 1 wire. The square back case will bolt right up and has marginal idle output ~50 amps. The GM guts alternator has ~ 80 amps idle output and is a tight fit with the heads at the output stud. No go with Ed heads in my application (400 core, factory brackets, with AC). It may fit with OE heads.

There are newer offerings that are advertised to fit and spendy (Flaming River, Green Alternators, Others). I am currently running the "big Chrysler" 100+ amp alternator with matching brackets from my core '78 Cordoba 400 engine. Good output and heavy.