What we usually recommend is the FX850V-AS12R, which is used in the new models and will fit the old frame. This engine comes with the air cleaner package. I doubt that the older FX850V with spec BS08-R is available. They could try. The new engine would require a new oil cooler mount and muffler. Your Hustler dealer should have access to the parts to install the new engine. You would need to go to an early 2010 XR7 super z parts manual with the engine package for the part numbers. By going to hustlerturf.com you'll find links at the bottom for the service and parts manuals. Then you would need to get the engine through Kawasaki Product Service Representative. Check out all the prices before you make that leap.