Uh, there's a drain plug in the tank. Let the truck sit and settle, and make sure it's level, or at least that the drain is at the low point, and pull the plug (you're supposed to use a new copper crush gasket each time) and let the water drain until the gas is water free, or just drain all of it. Crank the motor with both fuel lines removed from the carb until the lines are dry. Replace the fuel lines, but you can keep the line from filter to pump free to prime the fuel pump out of a jar with the coil wire shorted to ground. Go to the drugstore and buy a bottle of isopropyl rubbing alcohol and pour it in the plugged tank. Add at least 5gal of gas. Crank that baby up. You may have to prime the fuel pump twice, but not likely. Also, after the fuel pump is primed, pump the accel pedal until the accel pump in the primary barrel is squirting gas, not water, to flush the carb bowl, then reprime the fuel pump to refill the bowl.
The rubbing alky adsorbs the remainin water (the drain plug has a short rim around it that makes it impossible to completely drain the tank) and then it gets burned up/evaporated and goes out the tail pipe without leaning out the mixture like a water/gas mix will. "Heet" and other fuel additives to prevent fuel line icing by "drying" up the water are mostly alky of some kind. I have used a wet/dry vac with a hook bent piece of 1/4" copper to vac out the remaining water, but if there is any fuel in it, you could go boom from motor brush sparks. In your case, it's almost certainly almost all water, and "safe". It's your <img src="/forums/images/graemlins/butwiggle.gif" alt="" />.