For maintenance, it’s up to you how far you want to go.
Carburetor- The carburetor should be completely dismantled, cleaned and rebuilt with new primer seals, and preferably a modified Mercury float. The plastic Mercury float is a simple ethanol resistant replacement for the original cork float.
Ignition wires- often times have crumbling insulation or missing connectors. If necessary, new copper core wires can be carefully soldered to the coil buttons.
Ignition components-it’s not uncommon that all ignition components are still good. Inspect all components and clean contacts. Clean and reset points.
Starter-remove the starter and inspect the three tiny pawl springs. If all three are in place and not bent or broken then consider yourself lucky, otherwise they can be made. You may also need a new rope or recoil spring.
Water pump/intake seal-A new water pump is a necessity. Also inspect/replace the water tube grommet/seal. These seals can degrade and swell when immersed in water effectively blocking off the cooling water. Some prefer to trim them, but replacement is even better.
http://pochefamily.org/outboard/ -Lots of good information here.
Improvise-Adapt-Overcome
