I’d like to start replacing hose and oil, fuel lines of relatively unknown vintage.

Raw water intake hoses are definitely the newest, but the hoses between the pipe sections on the cooling system could stand to be replaced, if only for piece of mind.

Any advice? Where to start, common issues, etc…

Is this better as a winter project up north here or an in water project?

Engines are a pair of J/T 6-71Ns.

Thanks!