73 duster vented gas tank ?

Just heard back from Tanks Inc. The valve they offer will not work/function as an overfill valve. I have cancelled that order. This Atwood valve does mention overfill protection. The factory manual says the OE valve operates at 12-16in of water pressure
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"The limiting valve, which prevents overfilling the fuel tank, is made of brass, has a needle-type design, and operates at pressures of 12 to 16 inches of water pressure. It is located in the vapor vent line, (Fig. 1)"