There are going to be many nay-sayers about the OMC outdrives. If properly maintained they should last forever, like anything else they may require proper maintenance.
Pick up one of these:

found here:
http://www.amazon.com/OMC-Cobra-Stern-Drive-1986-98/dp/089330056XAlso
http://www.fourwinns.net for wiring diagrams etc on the boat. You can also call Four Winns and they can direct you to the correct part numbers as well as the places to find what remains of parts for these boats.
Only thing is parts may be a bit harder to come by, depending where you are located. I would get the water pump serviced and change the impeller etc. Make sure there is not any additional damage.
Best of luck! Glad to see more and more older Four Winns' popping up.
_________________
Rob

Present: 1999 Formula 280SS
Past: 1989 180 Horizon
http://www.robcamerondesign.com