All Rover manuals are available in pdf format from Rover.
http://www.rover.com.au/Page/Info-Centre/Owners-ManualsI have the 17HP version, the 28151, which is covered in the same manual. At the very least I think you will need to pull down and clean the carby, probably the rest of the fuel system as well, it is probably full of gum by now if it had fuel in it when it was parked two years ago. I have just replaced the front bushes in the deck slides on mine and turned the rear ones upside down to the unworn face. Just needing a new battery for it now to get back to some serious mowing.