First thing, disconnect fuel line supply to the carb, then check compression, throttle wide open. Put plug wires on grounding tabs by the rear ebox. From there, mix up some pre mix 40:1 and put some down the spark plug holes. Try and fire it. If it sounds good, get a section of fuel line and put it on the fuel pump, put the other side in the jug you mixed the pre-mix in. Now try and start it. If it runs for 20-30 seconds turn it off. Get the garden house ready to hook up to the ski, then start the ski, turn the hose on and run it for about a minute, monitor for leaks. Turn off the water, then turn off the engine. If it stalls you need to turn off the water, you could back fill the exhaust and fill the engine with water.
If you're good, order carb kits, fuel lines, and clean the tank. Then there's now oil system maintenance that needs to be done. Let's get it running first!