When you pull the junkyard alternator, take it to the nearest major auto parts store. Most auto parts stores will test alternators for free. Then have them bench test it on their alternator tester. That way you know it works and how much current and voltage it will put out.
Holy CHRIST with the spelling. I'm sitting here laughing. Go download Firefox, it'll check your spelling as you go.
I'm going to say something I'm sure I'll get flamed for. I've been running my stock alternator for 3 or 4 years now WITH under drive pulleys and WITH my e-fan. No problems. I was going to upgrade to a bigger alt, but if it aint broke, don't fix it, right?