Re: 1984 200hp ????
Ziggy,
Search the forum here,there is a lot of great information on this motor, and others of the era. Many of the blackmax motors of this error have a lot of interchangeable parts. Check the electrical over well. Also, take a compression gage with you and check compression. Acceptable for me is above 105psi per hole, no variance greater than 10psi in all holes.
IF you can, check the fluid in the LU as well, ensure there is no water in there or metal.
Also, talk with the owner about maintenance. If he is a real douche and suggest little to no maintenance 'Buyer Beware'. Yearly maintenance is needed for all outboards.
Other than the above, these are solid motors, very well built and should last a long time with proper care.
Good Luck I am looking for a new boat/motor right now as well.