Ok, so far this swap has been nearly bolt on, again 2009 26hp Briggs to 2011 27hp Kohler. I had to drill out the mounting holes on the engine mounting surface slightly, re-route the choke cable, I currently have the Kohler engine mounted, running, and throttle/choke cables adjusted. Next task will be the drive belt, followed by mounting the deck clutch and deck belt. Again, I can only hope those steps are as simple as the engine mounting.