I transcribed it (with added speakers' names) from my hard copy of Grube's 1974 translation, 2nd edition revised by Reeve in 1992. Agreed, I like the modern English fluency, and supposedly it's quite accurate, though I don't know enough Attic Greek to say myself.

Edit: Book VII, starting at 536d. You can compare against the public domain Jowett translation at http://classics.mit.edu/Plato/republic.8.vii.html (search in the page for "slave")