i wouldn't worry about that too much. the only thing electrical you should worry about is your starter, battery, and alternator. all the other wires will be fine under water or getting splashed. just make sure none of them touch or power touch ground.
Also you need to put silacone on you distributer cap to keep the water out. also they make a jelly type stuff that you can put in the end of you spark plug wires to keep the from corroding if you get them wet and it gives them better connectivity.