The LC 550 *should* work because it is most similar to the Colour Classic II. I can't promise you this, but I don't see any reason why it wouldn't.
That said, my Colour Classic has a Mystic LC 575 in it. In System 7.1 it kicks butt.
That said, my Colour Classic has a Mystic LC 575 in it. In System 7.1 it kicks butt.