They are exactly the same height, as they use the exact same case. I have an LCII, LCIII and LC475, and although my LCII uses the older auto-inject style case, they all have the exact same external dimensions.

Personally, i'd go with the LC475 myself...they're easy enough to find, offer great performance, and take well to upgrades. My 475 has a full '040, 36MB RAM, a 1 GB HDD and runs OS 8.1. Goes like the clappers, too, it does.