One wire alternator.

100amp would probably work but just keep in mind if your cars wiring is all factory....(and old) it was not intended to support a 100amp alternator per se. I'd go 60amp unless you plan on lots of upgrades (stereo, elec fans, fuel pump etc) and the requisite wiring upgrades (new/larger gauge etc). A relay kit for the headlights is a good idea! Those work great...it's up next on the list for my Duster. Using a bigger alt to brighten up the headlights is a little bit the "just shoot more ammo to hit the target" instead of better aim with one bullet approach. IMO...

Good luck! Both are good choices, and I'm sure some are running the 100amp with stock/old wiring without trouble but it's probably not ideal.

See Dan's (slantsixdan) expert and always entertaining opinion here (below)...and yes I dont know how to do cool embedded link on the word "here" like Dan does...but again, he's an expert. Maybe he'll chime in here re the alt question and destroy my only semi useful advice with a meat sandwhich of facts/links! Haha...

http://www.forabodiesonly.com/mopar/showthread.php?t=200609&highlight=headlight+relays