runamuck,
Do you have a fuel/water separator? If not, it's a good idea to install one even if you still have to re-route the fuel and vent lines. This way you can be fairly certain that contaminated fuel won't get to the engine. Another way to prevent/detect water in your gas is to install a sending unit from
WEMA , which will detect water before it gets from the tank to the water separator. Plus, you'll get a much more accurate reading on your fuel gauge.