Your biggest issue will be dirty fuel, lots and lots of dirty fuel. My mate in PNG runs Suzuki outboards however most natives run the old Yamaha Enduros. Whatever you get, make sure you put the best fuel/water separation filter and the finest particulate filter that you can get on your fuel line. Have spare filters and carry them. Teach yourself how to change a Water Pump impellor and buy a spare kit for that as well.