There's a similar thread on Kioti for a CK30. I have a 48" KK tiller for my CK27 gear which works fine and is offset enough to cover my tracks on one side. I can easily use all the power I have by increasing speed slightly. A number of posters suggest a 60 to 66 inch tiller.
We have the New Hawkline/International 60 inch for $1595 + modest shipping and the 72 inch "Tarter" for $1695 + shipping. Both with gear drive and slip clutch and 6 tines per rotor. Ken Sweet
Using the search function will bring up several discussions on tillers. I personally have a 60" King Cutter I use with my CT230 and it does a very nice job. I bought it at TSC on sale for $1299.