What we do when we resurect a boat from the dead:
Roll over engine to ensure it is not locked.
1. Change Oil and Filters, Note the conditon of the filters and the goo (hopefully not) on the inside of the filter housing.
2. Change Fuel Filters, observe as in #1.
3. Check heat exchangers or raw cooling pump. Check content of HE system, change out if even the least bit concerned. Top off with water.
4. Check out raw water cooling pump impellor. Most small ones are made of neoprene, change it out, dont even try to save it. The big ones used anything from cast iron (stupid) up to Nibral or SS. If it was cast iron, you might want to RUN, not walk from it.
5. Ensure fresh batteries or good air pressure.
6. Start engine up and check all vitals. After this you can determine if you want to keep it or trash it.
7. If you want to keep it, you can then spend the big money on redoing it the right way...new antifreeze, impellors, redo heat exchangers, etc.
Good Luck!