I think just about any fan you get will work, it's just a matter of how much air it will pull, and how mountable it is. I know of one person running an electric fan from a chevy cavalier.
I personally used a 3.8 Taurus fan.. from a late 80's/early 90's Ford Taurus (even the wagons have them.) It has to be the 3.8 engine though.. looking through junkyards here, I saw lots of 3.0's, but only a few 3.8's.
If you run the DCC controller like I do, you can basically run any fan you want, but the less air the fan can pull, the harder it's going to have to work to keep you running cool. The reason the Mark VIII and the Taurus fans are so popular, is because they pull an incredible amount of air, and line up almost perfectly with the bottom mounting slots, (meaning all you need to mount it is a few radiator pull through ties.) I don't remember the exact CFM rating, but the flex-a-lite and black magic electric fans claim 2400 or so, while I believe the taurus fan is several hundred CFM higher, and covers a much larger portion of the radiator. (And is much cheaper.)
The DCC unit gradually applies power to your fan, so you can run even on a stock alternator if need be, however upgrading to a 3g alternator isn't a bad idea if you haven't already done it. For an extra $5 you get a little LED light that tells you when and what speed the fan is running at.
And in case you're wondering, I was able to use the stock coolant overflow bottle in its stock position (curved on the right side of the fan, with some straps holding it down.)