I'm allways amazed when I see toys in that condition. I know he's your neighbor, and gave it to you (that was nice) but dam.... that's still a good hunk of $$$ just rotting.
Anyway... if it will crank... that's good. I would start with a compression check, to see if there is any life left in the engine.
Next... I would drain the fuel, and oil, and put in fresh. (replace the filters too) FYI... you need a good API-TC oil. DO NOT use "Outboard" oil in it. (TC-w3)
Then... I would pull the carbs, and clean them. (a lean run will be death to the engine)
Since it's a '95... make sure the driveshaft seal is OK. Put a few pumps of grease in it. If it's questionable... rebuild it. If you neglect it... and the internal bearing gives out... it will rip the boot, and you will have a 2" hole in the boat. (that will cause you to sink quickly)