Originally Posted by phidauex
In this case, I'd recommend your LBS. A wear item like a cassette won't be that much cheaper elsewhere, and you'll get valuable advice.
I'm having a hard time finding a reference for it, but I'm fairly certain that your RD will take up to a 28t, and likely a 30t. Your LBS should be able to find out for sure, and in the very least, slap something on and see if the B tension screw can be adjusted far enough out to work.
peace,
sam
Thanks Phidauex. I'm going to take all the advice here and go to my LBS with it. I did find the reference to the RD taking 28T. It is rated for that. The 30T they'll have to try out at the shop, as you said. I'm wondering if the difference between 28T and 30T is worth the effort to even check it out at this point.