Wow!..........
You just got an awesome buy! What a steal. There is nothing I would do as far as mod, just yet. This was one of the first 787cc engines that came out. I use this same engine in my 97 Challenger boat. My boat is awesome fast so I know the ski is even faster.
If it's only got 100 hours, then it's likely been sitting up a lot. You may be looking at rebuilding the carbs soon. Make sure that your not still using the grey fuel lines. These were removed and replaced years ago when they found the line broke down the rubber from the inside, choking off the fuel supply to the engine.
The first thing I'd do is clean it up, start it on the hose, then take it for a test spin checking to see that you have water coming from the "tell-tale". If you got the grey fuel lines, then you need to take care of that first.
There is a lot of info in here about this model ski and engine type. Oh, BTW, when you run these on the hose, the procedure is to start engine, then start water. To turn off, in the reverse order. If you just want to hear it fire, you can do that without the water. But only for a second or two. If it won't shut off, choke it.
When you attach the lanyard, you'll be wanting to listen up for 2 audible beeps. This signals that you have the correct lanyard. Anything other than that, holler back...........:cheers: