Before putting the new tank in, use either thinned epoxy or finishing epoxy to coat the inside of the fuselage in the area of the tank. This will fuelproof the wood and prevent damage in the future when (not if) you develop another leak. Also drilling a small hole in the bottom of the fuselage will allow fuel to drain out of the compartment and act as a "tell-tale" to let you know if there is another fuel leak.

Brad