pstr david

I have a 91 ford f150 4x4 with the inline six and a 5 speed. I am building this truck for fuel economy as I live in the island nation of Vanuatu and pay around $6 per gallon for gas! I need to pull a boat in and out of soft sandy beaches. The engine runs well now, but I want to freshen it up before shipping it over to this country. What are the best mods and best cam for fuel/ reliability?

thanks,
Dave